Fix the race condition for updating active catalogd when CatalogD HA is enabled

When CatalogD HA is enabled, statestored sends the address of current active catalogd to coordinators and catalogds during registration, or a new active catalogd is elected. Statestored sends the active catalogd in two different kinds of RPCs. If there are more than one election changes in short time, coordinators and catalogds could receive RPCs in the order which is different from the changing order on statestore. To make coordinators and catalogds to have same view as statestore, we have to avoid to overwrite the later version of active catalogd with previous change.