[DUBBO-3476]: NullPointerException happened when using SpringContainer.getContext() (#3600)

*     #3476: NullPointerException happened when using SpringContainer.getContext()

* rollback change for DEFAULT_SPRING_CONFIG

dubbo-container/dubbo-container-spring/src/main/java/org/apache/dubbo/container/spring/SpringContainer.java

@@ -46,7 +46,8 @@ public class SpringContainer implements Container {
         if (StringUtils.isEmpty(configPath)) {
             configPath = DEFAULT_SPRING_CONFIG;
         }
-        context = new ClassPathXmlApplicationContext(configPath.split("[,\\s]+"));
+        context = new ClassPathXmlApplicationContext(configPath.split("[,\\s]+"), false);
+        context.refresh();
         context.start();
     }