Geo: Test failover with object storage replication enabled

Summary

As more large customer begin to use Geo's beta object storage replication functionality, we want to ensure that it works as expected during a failover.

From a Slack thread on2021-05-06:

fabian 22 hours ago @gabriel @nick Nguyen @nick Westbury Do you know if we semi-recently tested a failover when Geo is replicating data in object storage (the beta feature)? If not, I’d argue we need to test this swiftly just to ensure that this all works as expected. Context is that more large customers are starting to use it. I am not saying anything is wrong, just that we should ensure we don’t have a blind spot.