RFC: Removed the default set PATH for Windows environments.

[danielGithinji]

This change is related to this PR: Don't set a default PATH for Windows.

Description:

This change seeks to remove the defaulted Windows image path found in util\system\path.go.

I used buildkit to create two images with following docker file contents:

FROM mcr.microsoft.com/windows/servercore:ltsc2022

RUN echo %PATH%

CMD ["powershell", "-Command", "Write-Host", "$env:PATH"]

For one image the PATH in util\system\path.go is defaulted to "c:\Windows\System32;c:\Windows" while for the other image the PATH is defaulted to an empty string.

• When you run the 1st image that contains the default path it gives the following result:

PS C:\Users\dgithinji> ctr run docker.io/gmanguru/fix-windows-path:withDefaultPath withDefaultPath
ctr: hcs::System::CreateProcess: powershell -Command Write-Host $env:PATH withDefaultPath: The system cannot find the file specified.: unknown

• While the 2nd image that has no PATH set gives the following result:

PS C:\Users\dgithinji> ctr run docker.io/gmanguru/fix-windows-path:NoDefaultPath NoDefaultPath
C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Users\ContainerAdministrator\AppData\Local\Microsoft\WindowsApps

In mcr.microsoft.com/windows/servercore:ltsc2022, PowerShell is available in "C:\Windows\System32\WindowsPowerShell\v1.0". When the PATH is defaulted to a specific value, application files for applications like PowerShell cannot be found/referenced hence the need to remove the defaulted path.