The `GET /images/json` requires an optional `container-count` parameter
which set the `Containers` property of in the ImageSummary to a number
of containers using that image.
This was also propagated to the new manifest list property which
includes a list of all the container IDs that are using this specific
image manifest.
Disconnect the `ImageData.Containers` property from this option and
always include it by default without an explicit opt-in.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
b93cf37dcd