Add verification job for gerrit@RBE

[davido]

It would be great to extend gerrit verification job to run also on RBE (like Bazel itself).

Something like this works for me:

  $ bazel test --config=remote --remote_instance_name=<project-name> javatests/...

This would help detect Bazel RBE regressions, e.g.: https://github.com/bazelbuild/bazel/issues/12705.