[llvm] [InlineCost] Disable cost-benefit when sample based PGO is used (PR #86626)

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WenleiHe wrote:

Thanks for working on profile maintenance. I don't think the patches you mentioned are going to change the results meaningfully. Is there a particular reason you want this to be default on? As others mentioned, you can just turn it on as needed. 

I'd also like to share some general feedbacks: 1) landing default changes like the original patch generally has a high bar. 2) the way it was done, without perf numbers, and without stakeholder review before landing is not how things are usually done. 

https://github.com/llvm/llvm-project/pull/86626