fix(net): modify drop node function

Author: xxo1shine

framework/src/main/java/org/tron/common/overlay/discover/table/NodeTable.java

@@ -74,7 +74,7 @@ public synchronized Node addNode(Node n) {
   public synchronized void dropNode(Node n) {
     NodeEntry entry = nodes.get(n.getHost());
     if (entry != null) {
-      nodes.remove(entry);
+      nodes.remove(n.getHost());
       buckets[getBucketId(entry)].dropNode(entry);
     }
   }

framework/src/test/java/org/tron/common/overlay/discover/table/NodeTableTest.java

@@ -21,7 +21,7 @@ public class NodeTableTest {
 
   @Test
   public void test() {
-    Node node1 = Node.instanceOf("127.0.0.1:10002");
+    Node node1 = Node.instanceOf("127.0.0.5:10002");
 
     NodeTable table = new NodeTable(node1);
     Node nodeTemp = table.getNode();