chore(java): install maven 3.8.1 at runtime (#1564)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* chore(java): install maven 3.8.1 at runtime

* chore: pin github action runner at ubuntu-16.04

* chore: install maven 3.8.1 at runtime

* chore: fix typo

Source-Author: Neenu Shaji <Neenu1995@users.noreply.github.com>
Source-Date: Thu Sep 2 15:46:06 2021 -0400
Source-Repo: googleapis/synthtool
Source-Sha: ad7fd76e17bf9494a3e47ff9cf445f61564432e0
Source-Link: googleapis/synthtool@ad7fd76

.github/workflows/ci.yaml

@@ -75,4 +75,4 @@ jobs:
     - run: java -version
     - run: .kokoro/build.sh
       env:
-        JOB_TYPE: clirr
+        JOB_TYPE: clirr

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquery.git",
-        "sha": "56e82d104be9d277c54afa2db6c91f4fc61b5382"
+        "sha": "c0dc007d47719f0ed43d21ba8af4d75f054e74d1"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "e2aa5bcc3356d9e3b8b53de3b5c86226447d3a22"
+        "sha": "ad7fd76e17bf9494a3e47ff9cf445f61564432e0"
       }
     }
   ],