Revert "Merge pull request #2218 from edx/max/aws-mongo"

This reverts commit f02f890a, reversing
changes made to 2c53e32c.

Reason: added to mongo play instead of mongo_3_0 play

playbooks/edx-east/mongo.yml

@@ -6,7 +6,6 @@
     serial_count: 1
   serial: "{{ serial_count }}"
   roles:
-    - aws
     - mongo
     - role: datadog
       when: COMMON_ENABLE_DATADOG