[clang] [NFC] [analyzer] Factor out SymbolManager::get<*> (PR #121781)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

I'm grateful for this code quality improvement, it's nice to see that you got rid of 180 lines of boilerplate :smile:

I have one minor inline suggestion that it would be nice to document the purpose of this new template method; but otherwise the change is straightforward and clearly LGTM. (Assuming that the deleted methods are not called elsewhere, which you obviously checked.)

https://github.com/llvm/llvm-project/pull/121781