Cluster: clusterSetStartupEpoch() made more generally useful.
Cluster: clusterSetStartupEpoch() made more generally useful.

The actual goal of the function was to get the max configEpoch found in
the cluster, so make it general by removing the assignment of the max
epoch to currentEpoch that is useful only at startup.

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis