amazon-ebs builder timeout error for AWS API endpoints

_This issue was originally opened by @ranjb as hashicorp/packer#6162. It was migrated here as a result of the [Packer plugin split](https://github.com/hashicorp/packer/issues/8610#issuecomment-770034737). The original body of the issue is below._

The amazon-ebs builder randomly times out when interacting with the AWS API. This can happen at any stage during the build, either at the beginning or at the end after the AMI is created and packer is trying to shut down the instance or sometimes when attempting to tag the AMI etc. The build script runs more than one packer build in sequence and sometimes the first one builds fine while it times out on the second or sometimes it fails right at the beginning of the first.

Example:
--> amazon-ebs: Error stopping instance: RequestError: send request failed
caused by: Post https://ec2.us-east-1.amazonaws.com/: dial tcp 54.239.28.176:443: i/o timeout

- Packer version 1.2.2
- Host platform: AWS Ubuntu 14.04 Docker container running on AWS via AWS CodeBuild
- Debug log using PACKER_LOG=1
https://gist.github.com/ranjb/cf8bd0d93242d4a935854acf2c4514de