[SE-5391] refactor: activate app servers before setting dns

[gabor-boros]

Description

This PR implements the monitoring changes introduced by NewRelic and causes provisioning issues.

Testing instructions

• check out the branch on Ocim stage
• run OpenEdXInstance.objects.get(id=965).enable_monitoring() in shell
• validate the monitoring items are set correctly in NewRelic
• validate that no critical or warning messages shown