[llvm] [AMDGPU] Move tryEffectiveStall to GCNSchedStrategy class, optionally use in tryPendingCandidate (PR #191924)

[Robert Imschweiler via llvm-commits]

ro-i wrote:

Ok, but shouldn't there be a test that uses the option then? I think that's also what Shilei was getting at

https://github.com/llvm/llvm-project/pull/191924