[llvm] [AMDGPU] Remove co-exec scheduler diagnostics. (PR #193724)

[Petr Kurapov via llvm-commits]

kurapov-peter wrote:

I have no preference. I can gate it by both gfx1250 and gfx950 as in the original patch. @arsenm? 

https://github.com/llvm/llvm-project/pull/193724