[clang] [analyzer][NFC] Make RegionStore dumps deterministic (PR #115615)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

LGTM overall, feel free to add these NFC improvements.

My only comment is a suggestion to define the comparison logic with a higher-level approach -- but the existing code is also OK if you prefer that.

https://github.com/llvm/llvm-project/pull/115615