We can set the storage and replication addresses differently for each of
the 3 swift-hosts.
swift-storage1 will use the "swift_storage_address" and
"swift_replication_address" values to set it's service and ring IPs.
swift-storage2 will use the default IPs calculated by finding the IP on
the appropriate interfaces (eth2 for storage and eth3 for replication).
swift-storage3 will use the swift_vars.storage_ip and swift_vars.repl_ip
vars to set it's service and ring IPs
This PR makes the gate more efficient by removing swift-storage4.
Depends-On: Iac72c99fc728fad82da65ae6c68a304e3d130bc1
Change-Id: I8f7eb551072a6cd6ad50c2a99c4dfc6652374efe
bfd73a50cc