[clang] [clang] Avoid -Wshadow warning when init-capture named same as class field (PR #74512)

[Mariya Podchishchaeva via cfe-commits]

Fznamznon wrote:

> And I'm not sure that it STOPS being confusing because of the lack of a capture of 'this'.

For that reason, I didn't fully disable the warning, and put it under `-Wshadow-uncaptured-local` flag instead.

https://github.com/llvm/llvm-project/pull/74512