Rollup merge of #110480 - whtahy:105107/known-bug-tests-for-unsound-issues, r=jackh726

Add `known-bug` tests for 11 unsound issues

r? ``@jackh726``

Should tests for other issues be in separate PRs?  Thanks.

Edit: Partially addresses #105107.  This PR adds `known-bug` tests for 11 unsound issues:
- #25860
- #49206
- #57893
- #84366
- #84533
- #84591
- #85099
- #98117
- #100041
- #100051
- #104005

Author: JohnTitor