[clang] [analyzer] Check the correct first and last elements in cstring.UninitializedRead (PR #95408)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

Overall I'm satisfied with this commit, but I have some minor remarks.

I'm publishing some review comments now, but I'll continue the review tomorrow.

https://github.com/llvm/llvm-project/pull/95408