[llvm] [X86] Correct Zen4 Scheduling References and Mismatches (PR #128030)

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bubblepipe wrote:

I have splitted this PR into [[NFC][X86] Correct Zen4 Scheduling (Part 1/2: Rename "19h" to "Zen4") #131615](https://github.com/llvm/llvm-project/pull/131615) and [[X86] Correct Zen4 Scheduling (Part 2/2: Functional Changes) #131616] (https://github.com/llvm/llvm-project/pull/131616)

https://github.com/llvm/llvm-project/pull/128030