Merge pull request #1264 from edx/derf/dont_PropagateAtLaunch_all_the_things

CloudFormation doesn't know what to do with these.

cloudformation_templates/edx-reference-architecture.json

@@ -2865,15 +2865,13 @@
             "Key":"environment",
             "Value":{
               "Ref":"EnvironmentTag"
-            },
-            "PropagateAtLaunch":true
+            }
           },
           {
             "Key":"deployment",
             "Value":{
               "Ref":"DeploymentTag"
-            },
-            "PropagateAtLaunch":true
+            }
           }
         ],
         "UserData": { "Fn::Base64" : { "Fn::Join" : ["", [