ci(build): Reduce maven 429 errors by using GCS Maven Mirror

[lqiu96]

Maven Central serves as a fallback for when GCS Mirror does not contain any artifact (most likely case: Artifact was just released and mirror did not replicate it yet).

Use settings.xml's profile to define a fallback: local .m2 -> gcs mirror -> maven central. Should be able to handle pulling in deps without overloading maven central

Fixes: #14171

[gemini-code-assist]

Code Review

This pull request configures the Google Maven Central Mirror in the root settings.xml using an active profile instead of mirrors, enabling a prioritized search chain with automatic fallback to Maven Central. Additionally, the downstream build script is updated to copy this configuration to the local ~/.m2 directory before running the build. Feedback suggests explicitly specifying the destination file path when copying settings.xml in the shell script to improve robustness.

[lqiu96]

429 error on the PR to try and reduce the 429's:

[ERROR] Plugin org.apache.maven.plugins:maven-install-plugin:3.1.4 or one of its dependencies could not be resolved:
[ERROR] 	The following artifacts could not be resolved: org.apache.maven.plugins:maven-install-plugin:pom:3.1.4 (present, but unavailable): Could not transfer artifact org.apache.maven.plugins:maven-install-plugin:pom:3.1.4 from/to central (https://repo.maven.apache.org/maven2): status code: 429, reason phrase: Too Many Requests (429)

Seems odd.. this should be in the maven mirror. Taking a look.

[blakeli0]

@suztomo I remember we decided not to use Google mirror at some point. What was the rational?