Use WaitLatch for {pre, post}_auth_delay instead of pg_usleep

When Who What
2021-07-29 00:52:31 Michael Paquier (michael-kun) Closed in commitfest 2021-09 with status: Rejected
2021-07-27 17:23:21 Nathan Bossart (bossartn) New status: Ready for Committer
2021-07-22 23:10:19 Nathan Bossart (bossartn) Added bossartn as reviewer
2021-07-15 14:25:45 Bharath Rupireddy (bharathrupireddy) Changed authors to Bharath Rupireddy (bharathrupireddy)
2021-07-15 14:25:32 Bharath Rupireddy (bharathrupireddy) Attached mail thread CALj2ACV6W-oeSUfEU38+pPu+cijknuUVCFV1psqSL5=bfpu3ZQ@mail.gmail.com
2021-07-15 14:25:32 Bharath Rupireddy (bharathrupireddy) Created patch record