[llvm] [MachinePipeliner] Limit the number of stores in BB (PR #154940)

[via llvm-commits]

llvmbot wrote:

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Failed to cherry-pick: [22b79fb](https://github.com/llvm/llvm-project/commit/22b79fb3b9d051a83520eaa9d03abad782697448)

https://github.com/llvm/llvm-project/actions/runs/18419192219

Please manually backport the fix and push it to your github fork.  Once this is done, please create a [pull request](https://github.com/llvm/llvm-project/compare)

https://github.com/llvm/llvm-project/pull/154940