fix: skip stats-aggregate job for docs-only changes (#88330)
## What?
Adds the docs-only change check to the `stats-aggregate` job.
## Why?
The `stats` job already skips work for docs-only changes using
`scripts/run-for-change.mjs`, but the `stats-aggregate` job was missing
this check. This caused unnecessary job runs when PRs only contain
documentation changes.
## How?
- Added the "Check non-docs only change" step (same pattern as the
`stats` job)
- Added conditional `if` checks to all subsequent steps
- Changed `fetch-depth` from 1 to 25 (required for the change detection
script to check commit history)
