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

[Ben Shi via cfe-commits]

benshi001 wrote:

How about only remove the second `return State` ? The removal of the first one may be less readable. But for the second one, it is very near to the final `return State`.  It may looks strange for very near `return State`s.

```
if () {
   return State;
}
return State;
```

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