[Provisioner] Support docker image with multiple region image_id

[cblmemo]

The current implementation of the docker image only supports a single region, i.e.

resources:
  image_id: docker:ubuntu

As discussed in #2574, we could allow multiple regions with docker image, even mixture of docker image and normal image:

resources:
  image_id:
    us-east-1: ami-xxx
    us-west-1: docker:ubuntu

[github-actions]

This issue is stale because it has been open 120 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[github-actions]

This issue is stale because it has been open 120 days with no activity. Remove stale label or comment or this will be closed in 10 days.