[clang] [clang] Rename -Wdeprecated-switch-case to -Wdeprecated-declarations-switch-case (PR #141779)

[Hans Wennborg via cfe-commits]

zmodem wrote:

Thanks! Ironically, ReleaseNotes.rst is where I started my patch, but I forgot to actually update it :)

https://github.com/llvm/llvm-project/pull/141779