[clang] [analyzer] Clean up evalBind, fix bad logic (PR #196313)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

At https://github.com/llvm/llvm-project/pull/194459#issuecomment-4347448898 I claimed that
> This is not just a theoretical concern – soon I will publish two unrelated non-NFC commits to fix logic errors where the coder misunderstood NodeBuilders.
– this is one of those two commits.

https://github.com/llvm/llvm-project/pull/196313