Added back DOCKER_HOST to gitlab CI

3 jobs for master in 1 minute and 40 seconds (queued for 43 seconds)
Status Job ID Name Coverage
  Build
passed #388
C
build:7-8.1

00:00:19

 
  Test
passed #389
C
test:7-8.1

00:00:20

 
  Docker
passed #390
docker
docker:7-8.1

00:01:00