AO3-6810 Don't send "Automatically flagged as spam" email when hiding works manually

[EchoEkhi]

Pull Request Checklist

• Have you read "How to write the perfect pull request"?
• Have you read the contributing guidelines?
• Have you added tests for any changed functionality?
• Have you added the Jira issue number
  as the first thing in your pull request title (e.g. AO3-1234 Fix thing)
• Do you have fewer than 5 pull requests already open? If not, please wait
  until they are reviewed and merged before creating new pull requests.

Issue

https://otwarchive.atlassian.net/browse/AO3-6810

Purpose

When manually hiding a work that has been marked as spam by Akismet or otherwise, don't send the "Automatically flagged as spam" email, send the "Your work has been hidden by the Policy & Abuse team" email.

Testing Instructions

See JIRA ticket.

Credit

EchoEkhi (He/him)