Downstream pipeline improvements (#1775)

- Set `--lockfile_mode=off` for downstream pipelines so that
https://github.com/bazelbuild/bazel/pull/20101 won't break Bazel in
downstream pipeline.
- Support filterting out build and test targets by `no_bazel_downstream`
tag in downstream pipelines, addressing
https://github.com/bazelbuild/rules_python/issues/1481#issuecomment-1768077511
2 files changed