PROD-839 Fix 2287 Spammed Discussion Content with documents are removed and unable to recover after unspam

[bb-yudhisthir]

Mark related activity as spam if topic/reply marked as spam instead earlier was deleting it which was permanently removing attachment

All Submissions:

• [x] Have you followed the Pull Requests Guidelines?
• [x] Does your code follow the WordPress' Coding Standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Fixes #2287.

How to test the changes in this Pull Request:

1. Go to any discussion and create a reply with the document
2. Mark as spam
3. The document gets removed and cannot be recovered even after unspam.

Proof Screenshots or Video

https://screencast-o-matic.com/watch/crQZ6rV64fK

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you written new tests for your changes, as applicable?
• [x] Have you successfully run tests with your changes locally?

Changelog entry

Mark related activity as spam if topic/reply marked as spam