[CELEBORN-1541] Enhance the readable address for internal port

### What changes were proposed in this pull request?
If the internal port is not defined, do not show the internal port(-1) in the readable address.

### Why are the changes needed?

If the workerInfo is applied for the RESTful request, such as curl `/api/v1/workers/exclude`, the internal port is always `-1`.

It is not necessary to show the `-1` in the readable address.

### Does this PR introduce _any_ user-facing change?
Just reduce the unnecessary info.

### How was this patch tested?

Not needed.

Closes apache#2659 from turboFei/internal_port.

Authored-by: Wang, Fei <[email protected]>
Signed-off-by: mingji <[email protected]>

common/src/main/scala/org/apache/celeborn/common/meta/WorkerInfo.scala

@@ -156,7 +156,8 @@ class WorkerInfo(
 
   def readableAddress(): String = {
     s"Host:$host:RpcPort:$rpcPort:PushPort:$pushPort:" +
-      s"FetchPort:$fetchPort:ReplicatePort:$replicatePort:$internalPort"
+      s"FetchPort:$fetchPort:ReplicatePort:$replicatePort" +
+      (if (internalPort > 0) s":InternalPort:$internalPort" else "")
   }
 
   def toUniqueId(): String = {