When removing project slugs, try to remove raw slugs too so we can remove old/invalid slugs

Summary:
Ref T10168. When we try to remove an additional hashtag, we remove the normalized version.

Instead, remove both the literal and normalized versions. This allows us to remove old/invalid slugs.

Test Plan: Removed garbage slugs like [,*,].

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10168

Differential Revision: https://secure.phabricator.com/D15048