[clang] [analyzer] Fix [[clang::suppress]] for template instantiations (PR #168954)

[Ziqing Luo via cfe-commits]

https://github.com/ziqingluo-90 approved this pull request.

The fix LGTM. 
I have one question for learning about how BugSuppression works though.

https://github.com/llvm/llvm-project/pull/168954