Force colocated Gradle home with project dir due to external resource relative path constraint

[jrodbx]

Part of #524

cc @kevinzheng-ap

Q: Why does Gradle cache go to C: while git does to D:?

A: According to https://github.com/actions/checkout

    # Relative path under $GITHUB_WORKSPACE to place the repository
    path: ''

in Github Actions yml:

    steps:
      - name: Echo envvars
        run: env

GITHUB_WORKSPACE=D:\a\paparazzi\paparazzi

Restore Gradle state from cache
  Received 117231600 of 117231600 (100.0%), 130.6 MBs/sec
  Cache Size: ~112 MB (117231600 B)
  "C:\Program Files\Git\usr\bin\tar.exe" -xf D:/a/_temp/c96358d7-feb9-49ca-b77f-16bc580e282f/cache.tzst -P -C D:/a/paparazzi/paparazzi --force-local --use-compress-program "zstd -d"
  Cache restored successfully
  Restored Gradle User Home from cache key: v7-gradle|Windows|build[43ab0e1a05934a87a85af6ae78be82bc]-864ae2f624330f224d5620539e20ac8ca1bddcb1
  Received 24560 of 24560 (100.0%), 0.3 MBs/sec
  Cache Size: ~0 MB (24560 B)
  "C:\Program Files\Git\usr\bin\tar.exe" -xf D:/a/_temp/d893dffd-b090-49f7-b98f-82c26d607026/cache.tzst -P -C D:/a/paparazzi/paparazzi --force-local --use-compress-program "zstd -d"
  Cache restored successfully
  Restored generated-gradle-jars with key generated-gradle-jars-631b98c57f67cf849e2976089ce526c6 to C:\Users\runneradmin\.gradle\caches\7.6\generated-gradle-jars\gradle-test-kit-7.6.jar

According to https://github.com/gradle/gradle-build-action

https://github.com/gradle/gradle-build-action/blob/d23c38fad3e837961b39af2b98b046694927aca4/src/setup-gradle.ts#L71-L77

HOME=C:\Users\runneradmin

GRADLE_USER_HOME
Specifies the Gradle user home directory (which defaults to /.gradle if not set).

[kevinzheng-ap]

Thanks for the quick fix

[TWiStErRob]

Reverted in #792