[clang] [NFC][analyzer] Eliminate NodeBuilder from ExprEngine visit methods and from their utility methods (PR #212186)

[Donát Nagy via cfe-commits]

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NagyDonat wrote:

Consider renaming `destNodes` to `Dst`. I know that this is unrelated to the core goals of this PR but let's remove an eyesore if we're here and modify most lines that use this variable.

https://github.com/llvm/llvm-project/pull/212186