infrastructure: set ami_id to match currently deployed server

This change updates the ami_id used for the ec2 instance to
match the one used on the currently deployed server in order
to prevent terraform from wanting to reprovision the entire system.

Change-Id: I04c7c4ff147b712fea74d569cc1f784a8433a150
tree: 06404921cc9c213962e8cf4e460506480375af9d
  1. .gitreview
  2. ecr.tf
  3. infra.tf
  4. main.tf
  5. README.txt