[AMDGPU][gfx12] Clean-up implementation of waits before SCOPE_SYS stores#150587

Pierre-vh merged 2 commits intomainllvm/llvm-project:mainfrom

users/pierre-vh/cleanup-wait-before-scope-sys-storellvm/llvm-project:users/pierre-vh/cleanup-wait-before-scope-sys-storeCopy head branch name to clipboard