[clang] [Clang] Remove the PackExpansion restrictions for rewrite substitution (PR #126206)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

I see the test references https://github.com/llvm/llvm-project/issues/124715 but you don't mention it in the summary and you don't have a release note. Does the test exercise the crash?

https://github.com/llvm/llvm-project/pull/126206