Verify GraphQL query supports all appropriate fields - Follow-up from "Add "Reviewers" to Vue MR list page"

The following discussion from !168422 (merged) should be addressed:

• @ms.mondrian started a discussion:

  issue (non-blocking): i found sorting by "priority" would error out and this is working when the flag is off. assuming this is out of the scope of this MR so marking this as non-blocking