Add CPU throttling to deletion
Add CPU throttling to deletion

Summary: Because our shards have repeatedly had performance issues, we should add CPU throttling to the deletion code. That way, we can deploy it and not have to worry about stopping it if we continue to have issues

Test Plan: unit tests. Will test on staging

Reviewers: emfree

Reviewed By: emfree

Differential Revision: https://phab.nylas.com/D2568

jobscore/sync-engine,closeio/nylas,jobscore/sync-engine,closeio/nylas,closeio/nylas,nylas/sync-engine,jobscore/sync-engine,nylas/sync-engine,nylas/sync-engine,closeio/nylas,jobscore/sync-engine,nylas/sync-engine