message: ci: add info about `test_saucelabs_bazel` being limited to master builds
  Follow-up to (see
  https://github.com/angular/angular/pull/31636#discussion_r305120859)
  PR Close
diff: @@ -245,6 +245,11 @@ jobs:
  path: dist/bin/packages/core/test/bundling/todo/bundle.min.js.br
  destination: core/todo/bundle.br
  + # This job is currently a PoC for running tests on SauceLabs via bazel. It runs a subset of the
  + # tests in `legacy-unit-tests-saucelabs` (see
  + # [BUILD.bazel](https://github.com/angular/angular/blob/ef44f51d5/BUILD.bazel#L66-L92)).
  + #
  + # NOTE: This is currently limited to master builds only. See the `default_workflow` configuration.
  test_saucelabs_bazel:
  <<: *job_defaults
  # In order to avoid the bottleneck of having a slow host machine, we acquire a better
  @@ -698,6 +703,10 @@ workflows:
  - test_saucelabs_bazel:
  requires:
  - setup
  + # This job is currently a PoC and a subset of `legacy-unit-tests-saucelabs`. Running on
  + # master only to avoid wasting resources.
  + #
  + # TODO: Run this job on all branches (including PRs) as soon as it is not a PoC.
  filters:
  branches:
  only: master
  