Geo replication can't be resumed after paused

Summary

!4331 (merged) introduced pause/resume for the Geo replication, however replication fails when resuming the DB replication because of a syntax error.

Steps to reproduce

Run:

gitlab-ctl geo-replication-pause
gitlab-ctl geo-replication-resume

root@geo-secondary:~# gitlab-ctl geo-replication-resume
* Resume replication
Postgres encountered an error: Unable to resume postgres replication

What is the current bug behavior?

Replication doesn't resume.

What is the expected correct behavior?

Replication should resume.

Relevant logs

Relevant logs

From /var/log/gitlab/postgresql/current

2020-07-30_09:44:22.96260 ERROR:  syntax error at or near "pg_wal_replay_resume" at character 1
2020-07-30_09:44:22.96263 STATEMENT:  pg_wal_replay_resume();

Details of package version

Provide the package version installation details

v13.2.1-ee

Configuration details

Provide the relevant sections of `/etc/gitlab/gitlab.rb`

Basic Geo secondary

Noted by Premium customer in ZD (internal only)

Workaround

Current workaround is to run the resuming manually using:

sudo gitlab-psql -c 'SELECT pg_wal_replay_resume();'
sudo gitlab-rake geo:replication:resume