[llvm] [AMDGCN] Allow unscheduling of bundled insns (PR #129769)

[Austin Kerbow via llvm-commits]

https://github.com/kerbowa commented:

It would be easier to test if there was a more reliable way to force reverting of scheduling, since the scheduler may change. You could probably create a more simple synthetic testcase.

Maybe just drop the mir test but keep the IR one with debug output so that you can check that the region actually has scheduling reverted.

https://github.com/llvm/llvm-project/pull/129769