When Redis is running as a slave, don't pass readiness probes until and unless the replica is fully synchronised.
This resolves the issue where, when Redis is upgraded, the replica is marked ready while still syncing from the master. This can lead to the master pod being terminated and restarted with no slaves ready to take over from it, leaving the Redis cluster failed until the original primary comes back up again.
What this PR does / why we need it:
When Redis is running as a slave, don't pass readiness probes until and unless the replica is fully synchronised.
This resolves the issue where, when Redis is upgraded, the replica is marked ready while still syncing from the master. This can lead to the master pod being terminated and restarted with no slaves ready to take over from it, leaving the Redis cluster failed until the original primary comes back up again.
Which issue this PR fixes
No issue created (yet).
Checklist
[stable/mychartname])