[llvm] Reapply "[CodeGen][NewPM] Port machine-branch-prob to new pass manager" (#96858) (PR #96869)

[Matt Arsenault via llvm-commits]

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+; RUN: llc -mtriple=x86_64-linux-gnu %s -stop-after=finalize-isel -o - | \
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arsenm wrote:

Apparently llc/new-pm/ has a requires X86 which is very surprising to me. In a follow up commit, should really move these under an X86 directory or use individual REQUIREs in the tests 

https://github.com/llvm/llvm-project/pull/96869