[clang] [analyzer] Avoid unnecessary super region invalidation in `CStringChecker` (PR #146212)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

According to the CI Checks, one of your testcases is failing:
https://github.com/llvm/llvm-project/actions/runs/16055061425?pr=146212
> error: 'expected-warning' diagnostics expected but not seen: 
  File /home/gha/actions-runner/_work/llvm-project/llvm-project/clang/test/Analysis/cstring-should-not-invalidate.cpp Line 106: TRUE
1 error generated.

https://github.com/llvm/llvm-project/pull/146212