ci/eval/compare: Improve performance and avoid large stacks

Various improvements such as:
1. Avoiding deduplications when there can't be any duplicates
2. Avoiding O(n^2) deduplications
3. Using builtins.any to avoid list allocations
4. Using builtins.concatMap instead of lib.flatten when it's known that there's only one level of nesting
5. Using builtins.groupBy instead of folding with an accumulator

In particular 5. should fix CI exceeding the stack size on staging: https://github.com/NixOS/nixpkgs/actions/runs/12989244871/job/36240781244?pr=377253

While 2. in particular should make CI a lot faster.

0 files changed, 0 insertions, 0 deletions