Dockerfiles: correct ENV format
Avoid docker warning:
- LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" formatMaintenance operation of our GitLab server is scheduled for Thursday, November 28 at noon. The server will be unavailable for about two hours.
Avoid docker warning:
- LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format