[llvm] [SimpleLoopUnswitch] Don't use BlockFrequencyInfo to skip cold loops (PR #159522)

[Luke Lau via llvm-commits]

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lukel97 wrote:

I've moved the existing test to PhaseOrdering to show how using PGOForceFunctionAttrs also prevents unswitching this loop

https://github.com/llvm/llvm-project/pull/159522