ruff

3c52d2d1 - Improve the performance of the formatter instability check job (#14471)

Improve the performance of the formatter instability check job (#14471) We should probably get rid of this entirely and subsume it's functionality in the normal ecosystem checks? I don't think we're using the black comparison tests anymore, but maybe someone wants it? There are a few major parts to this: 1. Making the formatter script idempotent, so it can be run repeatedly and is robust to changing commits 2. Reducing the overhead of the git operations, minimizing the data transfer 3. Parallelizing all the git operations by repository This reduces the setup time from 80s to 16s (locally). The initial motivation for idempotency was to include the repositories in the GitHub Actions cache. I'm not sure it's worth it yet — they're about 1GB and would consume our limited cache space. Regardless, it improves correctness for local invocations. The total runtime of the job is reduced from ~4m to ~3m. I also made some cosmetic changes to the output paths and such.