Allow evals to remove upperclasspeople from required signatures on request

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- [x] Semantic Issue: something about the meaning of the text is different
- [ ] Non-semantic Issue: Spelling, grammar, or formatting changes.

Summary of issue:

Evals should have the ability to remove upperclasspeople from packet under certain circumstances such that their signatures will count the same as alumni signatures or are not counted towards required signatures on packet.

This has been accepted practice for several years dating back to my frosh year 4 years ago (most commonly members asking to be taken off). Probably a good thing to codify.

PS no flame pls. Not inspired by recent events or anything (??), we just forgot to do it in the original rewrite project.