[clang] [clang][analyzer] Model more getline/getdelim pre and postconditions (PR #83027)

[Alejandro Álvarez Ayllón via cfe-commits]

https://github.com/alejandro-alvarez-sonarsource commented:

Applied the feedback.
By the way, when `StdLibraryFunctionsChecker` is refactored, I'd be happy to give a hand if you need updating these checkers (UnixAPI and Stream).

https://github.com/llvm/llvm-project/pull/83027