[llvm] [AMDGPU] Remove some Wave64 checks for GFX10+ MC tests (NFC) (PR #100971)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

Many of these are losing test coverage. They still should have separate wave32 and wave64 runs 

https://github.com/llvm/llvm-project/pull/100971