Fix blocked thread preventing applications from being downloaded on ApplicationStore startup

Change-Id: I40b80d7d0429d057fd8cda15109a1ae1fe006f74
diff --git a/core/store/dist/src/main/java/org/onosproject/store/app/DistributedApplicationStore.java b/core/store/dist/src/main/java/org/onosproject/store/app/DistributedApplicationStore.java
index c64942f..532b279 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/app/DistributedApplicationStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/app/DistributedApplicationStore.java
@@ -554,7 +554,7 @@
                             log.warn("Unable to fetch bits for application {} from node {}",
                                      app.id().name(), node.id());
                         }
-                    }, executor);
+                    }, messageHandlingExecutor);
         }
 
         try {