[clang] [clang][analyzer] Simplify code of StreamChecker (NFC). (PR #79312)

[Balázs Kéri via cfe-commits]

balazske wrote:

My concern was the addition of many small functions that are used only from few other `eval*` calls and are relatively special. And all of these need a common big set of arguments like `StreamSym`, `CE`, `Call`. The build of states for success and failure cases in the thing that is really special for the calls.
But I can make another solution with "helper" functions.

https://github.com/llvm/llvm-project/pull/79312