Prevent "mark instance as NSFW" from producing hellspawns

What does this PR do?

Prevent "mark instance as NSFW" from applying to boosts. This fixes a bug where boosts by a user from a NSFW instance are incorrectly converted into quotes despite existing as boosts on all remote instances (AKA hellspawns). Local users are able to react or reply to the fake "quote", but those activities are rejected by all remote instances. It's effectively a federation-killer.

Contribution Guidelines By submitting this merge request, you agree to follow our Contribution Guidelines

• I agree to follow this project's Contribution Guidelines
• I have made sure to test this pull request

UPGRADE_NOTES.md

 # Upgrade Notes
 
+## 2024.10.0
+
+### Hellspawns
+
+Sharkey versions before 2024.10 suffered from a bug in the "Mark instance as NSFW" feature.
+When a user from such an instance boosted a note, the boost would be converted to a hellspawn (pure renote with Content Warning).
+Hellspawns are buggy and do not properly federate, so it may be desirable to correct any that already exist in the database.
+The following script will correct any local or remote hellspawns in the database.
+
+```postgresql
+/* Remove "instance is marked as NSFW" hellspawns */
+UPDATE "note"
+SET "cw" = null
+WHERE
+	"renoteId" IS NOT NULL
+	AND "text" IS NULL
+	AND "cw" = 'Instance is marked as NSFW'
+	AND "replyId" IS NULL
+	AND "hasPoll" = false
+	AND "fileIds" = '{}';
+
+/* Fix legacy / user-created hellspawns */
+UPDATE "note"
+SET "text" = '.'
+WHERE
+	"renoteId" IS NOT NULL
+	AND "text" IS NULL
+	AND "cw" IS NOT NULL
+	AND "replyId" IS NULL
+	AND "hasPoll" = false
+	AND "fileIds" = '{}';
+```
+
 ## 2024.9.0
 
 ### Following Feed