[clang] [analyzer] Fix [[clang::suppress]] for nested templates (PR #183727)

[Donát Nagy via cfe-commits]

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

Thanks for the update!

I only have two very minor remarks (in inline comments), otherwise the commit LGTM :smile: Of course I still don't have a complete understanding of template wizardry ✨ but now the tests (which are now well-structured and easy to read) give me enough confidence to accept this PR.

https://github.com/llvm/llvm-project/pull/183727