Remove specific user mention on workflow label change to complete

What does this MR do and why?

Remove specific user mention on workflow label change to complete

• Use case: Sometimes I like to just let this automation change the workflow label for me after verification by merely closing the issue. However, before this change it mentioned me when I did this, adding a todo in my todo list. That caused me to have to then go and clear it. I do not think mentioning the user is specifically necessary for that or other used of this comment as the assigned person is likely already subscribed and will receive the notification. We do not need to make a sometimes intentional use of this automation add a todo for someone.

Expected impact & dry-runs

These are strongly recommended to assist reviewers and reduce the time to merge your change.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-policies-with-a-dry-run on how to perform dry-runs for new policies.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/doc/reactive/best_practices.md#use-the-sandbox-to-test-new-processors on how to make sure a new processor can be tested.

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (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 =>
  • Engineering week-in-review