redis: all sentinels specified in configuration are unreachable

Problem to solve

We are seeing a fair amount of an error

redis: all sentinels specified in configuration are unreachable

This can prevent new connections from agents and CI tunnels.

References

• Sentinel client code

Internal links

• Kibana: https://log.gprd.gitlab.net/goto/98366200-caf2-11ec-afaf-2bca15dfbf33
• Sentry: https://sentry.gitlab.net/gitlab/kas/?environment=gprd&query=is%3Aunresolved+all+sentinels+specified+in+configuration+are+unreachable&statsPeriod=14d