Clean up --gossip-port argument (#7067)

--gossip-port now specifies exactly that, the gossip port to use.  The
new --gossip-host argument can be used to specify the DNS name/IP
address for gossip if --entrypoint is not supplied (when --entrypoint is
supplied, the gossip address is automatically set to the node's ip
address as observed by the entrypoint)

net/remote/remote-node.sh

@@ -238,7 +238,8 @@ EOF
       multinode-demo/setup.sh "${args[@]}"
     fi
     args=(
-      --gossip-port "$entrypointIp":8001
+      --gossip-host "$entrypointIp"
+      --gossip-port 8001
       --init-complete-file "$initCompleteFile"
     )