[clang] [analyzer] Avoid use of `CallEvent`s with obsolete state (PR #160707)

[Artem Dergachev via cfe-commits]

haoNoQ wrote:

FWIW `getSValBeforeCall()` may still cause confusion. Eg., if multiple checkers process `checkPreCall()`, judging by the name you'd expect the returned state to be the state before *the first* checker callback invocation, as opposed to the state at the start of *your* checker callback invocation.

https://github.com/llvm/llvm-project/pull/160707