Docker Version update to docker-ce stable

[lukeb2e]

Issue Report

The current stable, beta and alpha channel are using an old docker version as seen on the release page. The used docker version should follow the docker-ce stable release more closely. I think the repository also changed to https://github.com/docker/engine instead of the currently tracked moby/moby.

Stable
2247.5.0

The Stable channel should be used by production clusters. 
Versions of CoreOS Container Linux are battle-tested within 
the Beta and Alpha channels before being promoted.

    kernel: 4.19.78
    rkt: 1.30.0
    docker: 18.06.3

Feature Request

Update the currently used docker version to docker-ce stable (19.03).

Environment

What hardware/cloud provider/hypervisor is being used to run Container Linux?
irrelevant

Desired Feature

Update the currently used repository https://github.com/coreos/docker/ to the docker-ce stable release.

Other Information

Current docker stable release: 19.03.4
CoreOS docker version: 18.06.3

[bgilbert]

We've tried a couple times to update to a newer Docker release, but encountered crashes that we weren't able to address. The history is in coreos/coreos-overlay#3477. There are no plans to update Docker to a newer version before Container Linux reaches end of life.