awsvip monitor returns success when it shall not

currently the aws_monitor returns sucess when it can grep the secondary_ip from the awscli describe instance response.
However, if the secondary private ip is a substring of the current primary private ip, it returns incorrectly success even when the secondary private ip is not attached to the instance.

Locate the aws_monitor implementation and inspect how the awscli describe-instance response is matched for the secondary_ip. Reproduce the case where that value is a substring of the primary private IP, then verify that monitor success occurs only when the secondary IP is actually attached.

Written by the indexing model from the issue text.