SERVER-53829 introduces this feature, but we do not have explicit test coverage. Should test that:

• listIndexes can run concurrently with a MODE_X collection lock holding operation.
• listCollections can run concurrently with a MODE_X database lock holding operation
  • ideally MODE_X db lock, but I'm not sure whether we have those anymore, so just proving that listCollections can run concurrently with a MODE_X collection lock on a collection that it returns in the report also proves lock-free operation.