ChangeRebuilderImpl: Actually save data

I missed calling execute() this when refactoring to add a method that
takes a NoteDbUpdateManager. This was causing RebuildNoteDb to finish
unrealistically quickly.

Change-Id: I21eb436259ae1d74f16351ce064345e123963943
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeRebuilderImpl.java b/gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeRebuilderImpl.java
index ee00093..4a0d56b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeRebuilderImpl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeRebuilderImpl.java
@@ -156,7 +156,9 @@
     NoteDbUpdateManager manager =
         updateManagerFactory.create(change.getProject());
     buildUpdates(manager, ChangeBundle.fromReviewDb(db, changeId));
-    return execute(db, changeId, manager);
+    NoteDbChangeState result = execute(db, changeId, manager);
+    manager.execute();
+    return result;
   }
 
   private NoteDbChangeState execute(ReviewDb db, Change.Id changeId,