[Coroutines] Fix a few failing tests
Summary:
https://reviews.llvm.org/D82029 introduced the non-throw check for final_suspend(). There are a few tests I missed in that patch.
Fixing them here.
Reviewers: #libc, lewissbaker, modocache, ldionne
Reviewed By: #libc, ldionne
Subscribers: dexonsmith, modocache, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D82338