Remove unused global secondary index on subscriptions table (#1415)

In #1410 a new index was added to replace the one removed here (it's the
same, but also includes the platform). Since #1409 we've been using the
new index, so now the old index can be removed.

cloudformation.yaml

@@ -1105,7 +1105,6 @@ Resources:
               Action:
                 - "dynamodb:Scan"
               Resource:
-                - !Sub arn:aws:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${App}-${Stage}-subscriptions/index/ios-endTimestamp-revalidation-index
                 - !Sub arn:aws:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${App}-${Stage}-subscriptions/index/ios-endTimestamp-revalidation-index-with-platform
                 - !Sub arn:aws:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${App}-${Stage}-subscriptions
         - PolicyName: sqs

dynamo.cloudformation.yaml

@@ -84,17 +84,6 @@ Resources:
       StreamSpecification:
         StreamViewType: NEW_AND_OLD_IMAGES
       GlobalSecondaryIndexes:
-        - IndexName: ios-endTimestamp-revalidation-index
-          KeySchema:
-            - AttributeName: subscriptionId
-              KeyType: HASH
-            - AttributeName: endTimestamp
-              KeyType: RANGE
-          Projection:
-            NonKeyAttributes:
-              - autoRenewing
-              - receipt
-            ProjectionType: INCLUDE
         - IndexName: ios-endTimestamp-revalidation-index-with-platform
           KeySchema:
             - AttributeName: subscriptionId