record exception in dubbo high version (#5892)

Author: tydhot

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/TracingFilter.java

@@ -63,7 +63,7 @@ public Result invoke(Invoker<?> invoker, Invocation invocation) {
       throw e;
     }
     if (isSynchronous) {
-      instrumenter.end(context, request, result, null);
+      instrumenter.end(context, request, result, result.getException());
     }
     return result;
   }