Update for OpenCI migration

- Upgrade packer as it is way too old to support IAM based authentication
- Add VPC_ID and SUBNET_ID in environment variables to support multiple
  infrastructure like DEV, TEST, PROD etc
- Add "packer_" tags to identify instances spun up by packer.
- Increase node size as Docker images are getting bigger

Signed-off-by: Saheer Babu <saheer.babu@arm.com>
5 files changed