Fix Gradle version compatibility issues for Android

[tustanivsky]

This PR addresses build errors encountered when targeting Android Shipping configuration. These issues were introduced by recent updates to:

• Android SDK v8.30.0 (chore(deps): update Java SDK (Android) to v8.30.0 #1196)
• Sentry Android Gradle Plugin v6.0.0 (chore(deps): update Android Gradle Plugin to v6.0.0 #1208)

Note: On Android, debug symbol upload occurs only when packaging the Shipping configuration with For Distribution flag checked. For this reason, it has to be enabled in CI to properly verify that the Sentry's Android Gradle plugin behaves as expected.

Key changes

• Added Shipping configuration to Android build targets list in CI
• Added the protobuf-javalite dependency required for the tombstone integration feature (feat: minimal tombstone integration sentry-java#4933)
• Enabled overriding the engine’s default Gradle version for UE 5.5+
• Set the default Gradle version to v8.14.2 to align with the version used by the
  Sentry Android Gradle plugin
• Removed automatic symbol upload configuration via environment variable in CI scrips and enabled it in sample project settings instead (in Android UPL file we can't read env vars).

#skip-changelog

[github-actions]

Semver Impact of This PR

⚪ None (no version bump detected)

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