Fix policy for removing Accepting Merge Requests

Summary

As noticed by @godfat-gitlab, the policy for removing the Accepting Merge Requests label did not remove the label from issues with invalid workflow labels unless they were assigned, which is rare. This fixes that bug so the label is removed regardless of assignee. This is expected to cause hundreds and perhaps thousands of 97 issues to have the label removed.

Background: That condition was implemented in Commit cc0508e2, and this MR moves it from the shared conditions to the policy-specific conditions.

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • [] /cc @person_or_group =>
  • Relevant Slack channels =>
  • Week-in-review