Skip ecosystem check when no changes detected

[T-256]

Summary

For example, #8512 doesn't need ecosystem check

Test Plan

[zanieb]

Hm okay, I'm not sure saving the 50s is critical but why not :) thanks!

[zanieb]

@T-256 it doesn't show up until after its needs jobs complete.

All of these checks are expected to run when the workflow itself is modified.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.