[Fix] hbase cleint close report error in multi-thread environment (#139)

Author: shenyunlong

src/main/java/com/alipay/oceanbase/hbase/OHTable.java

@@ -1543,7 +1543,6 @@ public void close() throws IOException {
         if (cleanupPoolOnClose) {
             executePool.shutdown();
         }
-        ObTableClientManager.clear();
     }
 
     @Override

src/main/java/com/alipay/oceanbase/hbase/util/ObTableClientManager.java

@@ -128,17 +128,6 @@ public static ObTableClient getOrCreateObTableClient(ObTableClientKey obTableCli
         return OB_TABLE_CLIENT_INSTANCE.get(obTableClientKey);
     }
 
-    public static void clear() throws IOException {
-        try {
-            for (Map.Entry<ObTableClientKey, ObTableClient> pair : OB_TABLE_CLIENT_INSTANCE.entrySet()) {
-                pair.getValue().close();
-            }
-        } catch (Exception e) {
-            throw new IOException("fail to close tableClient" , e);
-        }
-        OB_TABLE_CLIENT_INSTANCE.clear();
-    }
-
     public static class ObTableClientKey {
         private String     paramUrl;
         private String     fullUserName;