[llvm] LoopSimplify: strip unused pass dependencies (NFC) (PR #107379)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> The legacy pass is still used by the backend, and at least some of these preservations are important.

The CI failures should be fixed now, but how can we be confident that the patch is correct? What is this mysterious preservation?

https://github.com/llvm/llvm-project/pull/107379