Make BGREWRITEAOF actually best-effort
Created by: efritz
I upgraded my brew packages which changed the configuration of my redis instance. After this the frontend failed to start up with no messages (just failed configuration pings from all other services).
This PR fixes a comment that claims a "best-effort" operation to be actually "best-effort". The BGREWRITEAOF command will return an error if the redis instance cannot persist to disk, which will cause the sysreq to keep retrying until it exceeds a deadline.
This change will simply log the error if it can successfully reach the redis instance, which will allow the frontend to start up.