Remove connection from thread local at close

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/operation/mgt/dao/OperationManagementDAOFactory.java

@@ -94,6 +94,7 @@ public class OperationManagementDAOFactory {
         } catch (SQLException e) {
             log.error("Error occurred while close the connection");
         }
+        currentConnection.remove();
     }
 
     public static void commitTransaction() throws OperationManagementDAOException {