Merge branch 'ps/ref-tests-update'

Merge branch 'ps/ref-tests-update'

Update ref-related tests.

* ps/ref-tests-update:
  t: mark several tests that assume the files backend with REFFILES
  t7900: assert the absence of refs via git-for-each-ref(1)
  t7300: assert exact states of repo
  t4207: delete replace references via git-update-ref(1)
  t1450: convert tests to remove worktrees via git-worktree(1)
  t: convert tests to not access reflog via the filesystem
  t: convert tests to not access symrefs via the filesystem
  t: convert tests to not write references via the filesystem
  t: allow skipping expected object ID in `ref-store update-ref`