AO3-6564 Strip images from more fields

[brianjaustin]

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Issue

https://otwarchive.atlassian.net/browse/AO3-6564

Purpose

Strip images in a few funky places, in addition to the original PR (#4729)

• automatic replies to abuse reports (the Zoho side already should strip)
• automatic replies to feedback/support requests (same re Zoho)
• inbox comments for replies to comments on admin/news posts