[FAB-8688] Gossip onConnect() references wrong field

In gossip, when a peer p contacts peer q and tries to connect
to it, while it's already connected to it - q closes the current
connection with p and replaces it with q.

However, the code referenced the identity field instead of the
pki-id field and thus it always replaced the connection,
without closing the previous connection.

Change-Id: I021ce246ce3735aa9e3451f20590fd119737a310
Signed-off-by: yacovm <yacovm@il.ibm.com>

gossip/comm/conn.go

@@ -167,7 +167,7 @@ func (cs *connectionStore) onConnected(serverStream proto.Gossip_GossipStreamSer
 	cs.Lock()
 	defer cs.Unlock()
 
-	if c, exists := cs.pki2Conn[string(connInfo.Identity)]; exists {
+	if c, exists := cs.pki2Conn[string(connInfo.ID)]; exists {
 		c.close()
 	}