Fix rds ingress groups.

cloudformation_templates/edx-reference-architecture.json

@@ -3826,10 +3826,14 @@
           {
             "EC2SecurityGroupId":{
               "Ref":"EdxappServerSecurityGroup"
-            },
+            }
+          },
+          {
             "EC2SecurityGroupId":{
               "Ref":"WorkerServerSecurityGroup"
-            },
+            }
+          },
+          {
             "EC2SecurityGroupId":{
               "Ref":"XqueueServerSecurityGroup"
             }