[terraform] Run automatic identity search sync cron task

Summary:
This automatically runs the identity sync-identity-search command once a day at midnight UTC

Depends on D11161

Test Plan: Just terraform applied on staging. Won't land until confirmed working functionally

Reviewers: varun, marcin

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11125