Summary:
Removes unused suppressions before deploying 0.91. See D13708161 for more context on why these couldn't be removed before.
I will follow up with 2 more diffs:
1. A diff that bumps the flow version in xplat and removes unused suppressions
2. A diff that adds new suppressions for 0.91
Reviewed By: samwgoldman
Differential Revision: D13720219
fbshipit-source-id: b07dd163962fed7ff27ce3e0a4a73a71c51965d9