[clang] [Clang][Sema] Revisit the fix for the lambda within a type alias template decl (PR #89934)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

> We are missing a changelog entry though

No release entry because this was intended to be a fix for 19 regression and we now want to backport it :)

https://github.com/llvm/llvm-project/pull/89934