Update to use Docker Image

Renovate does not support the current resource download being used by the hardening manifest, and so updates are not happening in a timely manner.

The enterprise version tracks the docker image: mattermost/mattermost-enterprise-edition.

We should investigate why this team version isn't tracking the docker image mattermost/mattermost-team-edition instead of https://releases.mattermost.com. Renovate has a datasource for docker, but not for releases.mattermost.com.

If feasible, we should update the hardening manifest and Dockerfile to leverage the upstream docker hub image for team edition so we can receive updates and MRs via renovate-bot. If there is a reason for why team builds differently then we should document that for future reference.

Secondarily, we need to document in Confluence why we have both an enterprise and team version in Iron Bank, who uses them within P1, and who is responsible for testing and deploying updates.

• Does P1 use team or enterprise?
• Does anyone outside of P1 use enterprise?
• Are both versions in use?
  • If not, should we be maintaining both versions?