[clang] [Clang] Extend lifetime of temporaries in mem-default-init for P2718R0 (PR #86960)

[via cfe-commits]

https://github.com/cor3ntin approved this pull request.

LGTM
But you need a release note to say that the implementation of P2718R0 is complete

https://github.com/llvm/llvm-project/pull/86960