[llvm] [CodeGen] Fix profiled triangular CFG threshold in MachineBlockPlacement (PR #188752)

[via llvm-commits]

worthlane wrote:

@arsenm Auto-merge is enabled, but the required Linux/Windows checks are still stuck at “Expected — Waiting for status to be reported”. Should I update/rebase the branch, or does this need action from a maintainer?

https://github.com/llvm/llvm-project/pull/188752