Run regeneration-check in Lefthook pre-push hook

What does this MR do and why?

This should avoid catching these too late (in the MR), e.g. !1695 (comment 1127114434).

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review