volume.balance: add delay during tight loop

fix https://github.com/chrislusf/seaweedfs/issues/2637

weed/shell/command_volume_fix_replication.go

@@ -75,7 +75,7 @@ func (c *commandVolumeFixReplication) Do(args []string, commandEnv *CommandEnv,
 		fixedVolumeReplicas := map[string]int{}
 
 		// collect topology information
-		topologyInfo, _, err := collectTopologyInfo(commandEnv)
+		topologyInfo, _, err := collectTopologyInfo(commandEnv, 15*time.Second)
 		if err != nil {
 			return err
 		}