Broken master `cache gems: needs 'setup-test-env pg10'` when commit only has QA changes

https://gitlab.com/gitlab-org/gitlab/pipelines/136762929

Found errors in your .gitlab-ci.yml:
cache gems: needs 'setup-test-env pg10'
You can also test your .gitlab-ci.yml in CI Lint

setup-test-env pg10 only runs for master with code/backstage changes:

• https://gitlab.com/gitlab-org/gitlab/-/blob/090f4d1fc0f78f37be1c1051b97e46385adf363a/.gitlab/ci/rails.gitlab-ci.yml#L37
• https://gitlab.com/gitlab-org/gitlab/-/blob/090f4d1fc0f78f37be1c1051b97e46385adf363a/.gitlab/ci/rules.gitlab-ci.yml#L359-364

But we now test against PG11 by default, so cache gems should rely on setup-test-env pg11 since it runs for QA changes as well: https://gitlab.com/gitlab-org/gitlab/-/blob/090f4d1fc0f78f37be1c1051b97e46385adf363a/.gitlab/ci/rules.gitlab-ci.yml#L533