EC2 Watcher Rate Limited

[zpritcha]

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Description of issue:

We're missing some EC2 instances in AWS that are not in SM's database. We've also seen instances where an instance has been running for 6+ months but SM reports the instance was last seen ~1 month ago. Additionally there aren't any AWS access issues in the logs, so I don't believe that's part of the issue.

Due to the large number of accounts and EC2 instances we have, we believe the EC2 watcher is getting rate limited.

Opening this issue for tracking purposes to link to an eventual PR that migrates the current watcher over to Cloudaux.