ci: try to fix AppVeyor failure due to outdated Maven version

[galtm]

This PR is a "blind" attempt to set a newer Maven version than 3.6.0 in the AppVeyor test run, on top of all the changes for #1833. I don't know how to test this without making a pull request, so it's an experiment.

Removing test\ci\run-core-tests.cmd from appveyor.yml is just a way to ensure that the build doesn't time out before we find out whether the Maven packaging worked. If all goes well, I'll restore that line.

If it works: Fixes #1893

[galtm]

The simplest thing didn't work. Although there is an environment variable MAVEN_VERSION with value 3.8.7, we're still getting 3.6.0.

=== Print Maven version
Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T18:41:47Z)
Maven home: C:\Program Files (x86)\Apache\Maven\bin\..
Java version: 1.8.0_162, vendor: Oracle Corporation, runtime: C:\Progra~1\Java\jdk1.8.0\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows server 2012 r2", version: "6.3", arch: "amd64", family: "windows"

Maven is not mentioned on https://www.appveyor.com/updates/

[galtm]

@cmarchand , is this something you're familiar with?

[galtm]

Do we need to include commands to install Maven when the version we get by default isn't the one we want? Here's an example: https://github.com/Riverside-Software/sonarlint-eclipse/blob/629c37e33e7eed6ac56ddbaa7d569579d9bf1885/appveyor.yml#L5

[galtm]

When I tried adding installation commands, they appeared to take effect

[00:00:13] maven v3.8.7 [Approved]
[00:00:13] maven package files install completed. Performing other installation steps.
[00:00:14] C:\Users\appveyor\.m2
[00:00:15] PATH environment variable does not have C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.7\bin in it. Adding...
[00:00:15] Environment Vars (like PATH) have changed. Close/reopen your shell to
[00:00:15]  see the changes (or in powershell/cmd.exe just type `refreshenv`).
[00:00:16]  The install of maven was successful.
[00:00:16]   Software installed to 'C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.7'
[00:00:16] 
[00:00:16] Chocolatey installed 1/1 packages. 
[00:00:16]  See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).
[00:00:16] SET PATH=C:\ProgramData\chocolatey\lib\maven\apache-maven-%MAVEN_VERSION%\bin;%PATH%
[00:00:16] refreshenv
[00:00:17] Refreshing environment variables from registry for cmd.exe. Please wait...Finished..
[00:00:17] mvn --version
[00:00:18] Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T18:41:47Z)
[00:00:18] Maven home: C:\Program Files (x86)\Apache\Maven\bin\..
[00:00:18] Java version: 1.8.0_162, vendor: Oracle Corporation, runtime: C:\Progra~1\Java\jdk1.8.0\jre
[00:00:18] Default locale: en_US, platform encoding: Cp1252
[00:00:18] OS name: "windows server 2012 r2", version: "6.3", arch: "amd64", family: "windows"
[00:00:18] echo %PATH%
[00:00:18] C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\wbin;C:\Perl\site\bin;C:\Perl\bin;C:\windows\system32;C:\windows;C:\windows\System32\Wbem;C:\windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\bin;C:\Program Files\Google\Compute Engine\sysprep\;C:\Program Files\Google\Compute Engine\metadata_scripts\;C:\Program Files\Microsoft\Web Platform Installer\;C:\Tools\GitVersion;C:\Tools\PsTools;C:\Program Files\7-Zip;C:\Program Files\Mercurial;C:\Program Files (x86)\Subversion\bin;C:\Program Files\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\110\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files\Microsoft SQL Server\120\DTS\Binn\;C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.4\;C:\Program Files (x86)\Microsoft SDKs\Azure\CLI\wbin;C:\Tools\WebDriver;C:\Tools\NUnit\bin;C:\Tools\xUnit;C:\Tools\MSpec;C:\Tools\Coverity\bin;C:\Program Files\nodejs;C:\Program Files (x86)\iojs;C:\Program Files\iojs;C:\Users\appveyor\AppData\Roaming\npm;C:\Program Files (x86)\CMake\bin;C:\go\bin;C:\Program Files\Java\jdk1.8.0\bin;C:\Python27;C:\Ruby193\bin;C:\Users\appveyor\.dnx\bin;C:\Program Files (x86)\MSBuild\14.0\Bin;C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\CommonExtensions\Microsoft\TestWindow;C:\Tools\NuGet3;C:\Program Files (x86)\Microsoft SQL Server\120\Tools\Binn\ManagementStudio\;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\PrivateAssemblies\;C:\Program Files (x86)\Microsoft SQL Server\120\DTS\Binn\;C:\Program Files\Microsoft SQL Server\130\Tools\Binn\;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\130\Tools\Binn\;C:\Program Files\Git LFS;C:\Program Files\Microsoft DNX\Dnvm\;C:\Program Files (x86)\Microsoft SQL Server\130\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\130\DTS\Binn\;C:\Program Files\Microsoft SQL Server\130\DTS\Binn\;C:\Program Files (x86)\Microsoft SQL Server\110\DTS\Binn\;C:\Program Files (x86)\Apache\Maven\bin;C:\Python27\Scripts;C:\Tools\NUnit3;C:\Program Files\Mercurial\;C:\Program Files\dotnet\;C:\Tools\curl\bin;C:\Program Files (x86)\Microsoft SQL Server\140\DTS\Binn\;C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\Extensions\Microsoft\SQLDB\DAC\130;C:\Tools\vcpkg;C:\Program Files (x86)\Microsoft SQL Server\140\Tools\Binn\;C:\Program Files\Microsoft SQL Server\140\Tools\Binn\;C:\Program Files\Microsoft SQL Server\140\DTS\Binn\;C:\Program Files\erl9.2\bin;C:\Program Files (x86)\NSIS;C:\Tools\Octopus;C:\Program Files\LLVM\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\;C:\Program Files\PowerShell\6\;C:\Program Files (x86)\nodejs\;C:\Program Files\Git\cmd;C:\Program Files\Git\usr\bin;C:\Program Files\Meson\;C:\ProgramData\chocolatey\bin;C:\Program Files\Amazon\AWSCLI\;C:\Program Files (x86)\Yarn\bin\;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.7\bin;;C:\Users\appveyor\.dnx\runtimes\dnx-clr-win-x86.1.0.0-rc1-final\bin;C:\Users\appveyor\.dotnet\tools;C:\Users\appveyor\AppData\Roaming\npm;C:\Users\appveyor\AppData\Local\Yarn\bin

but Maven is still running 3.6.0 from a different location that comes first in the path:

Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T18:41:47Z)
Maven home: C:\Program Files (x86)\Apache\Maven\bin\..

[cmarchand]

I'll try to have a look at this tonight. I'm on holidays now, ut I think I'll be able to put 30' on this this evening...

[galtm]

I'll try to have a look at this tonight. I'm on holidays now, ut I think I'll be able to put 30' on this this evening...

Thank you!!

[galtm]

To enable #1833 to avoid the failure we're investigating here, I disabled the Maven operations in AppVeyor (ee4ba74) as part of that PR. I'm mentioning this for 2 reasons:

• It's related to the merge conflict that GitHub is flagging.
• I wanted you to know about that commit in case you rebase on top of master or something. You wouldn't want to be surprised to find that the Maven operations aren't running.