[clang] [clang][analyzer][NFC] Remove redundant code in StreamChecker (PR #71394)

[Balázs Kéri via cfe-commits]

balazske wrote:

This change looks not very useful to me. These removed return statements indicate that at the end of the `if` branch there is no more work to do in this function, and it reduces complexity (less execution paths). The code becomes a bit shorter but not necessarily more easy to understand. Optimizing code for execution speed or binary size is not important because I am sure that compiler optimizations can handle this case.

https://github.com/llvm/llvm-project/pull/71394