build(ci): add bulkTests profile to grpc-gcp-java

[lqiu96]

grpc-gcp-java has its own split-units config. BulkTests filter should ignore those unit tests from running on the units CI

[INFO] --- surefire:3.5.2:test (default-test) @ grpc-gcp ---
[INFO] Using auto detected provider org.apache.maven.surefire.junit4.JUnit4Provider
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.google.cloud.grpc.ChannelIdPropagationTest
[INFO] Running com.google.cloud.grpc.GcpManagedChannelOtelMetricsTest
[INFO] Running com.google.cloud.grpc.GcpManagedChannelTest

Logs of it running in units CI.

[gemini-code-assist]

Code Review

This pull request adds a 'bulkTests' profile to skip tests across numerous POM files in various submodules. The reviewer recommends defining this profile in the parent POM instead of duplicating it in every submodule, which would leverage Maven inheritance to reduce boilerplate and simplify maintenance.