Remove ruby-2.7.2-git-2.29-chrome-85-node-12.18-yarn-1.22-docker-19.03.1 images

Deprecates the 6 following images:

• ruby-2.6.5-git-2.29-chrome-74.0-node-12.18-yarn-1.22-docker-19.03.1
• ruby-2.6.5-git-2.29-chrome-85-node-12.18-yarn-1.22-docker-19.03.1
• ruby-2.7.2-git-2.29-chrome-85-node-12.18-yarn-1.22-docker-19.03.1
• ruby-2.6.5-git-2.31-chrome-74.0-node-12.18-yarn-1.22-docker-19.03.1
• ruby-2.6.5-git-2.31-chrome-85-node-12.18-yarn-1.22-docker-19.03.1
• ruby-2.7.2-git-2.31-chrome-85-node-12.18-yarn-1.22-docker-19.03.1

The script named as scripts/install-docker and its relevant docs are left as is to re-use in the near future.

Investigation

• https://sourcegraph.com/search?q=repo:gitlab.com/gitlab-org+registry.gitlab.com/gitlab-org/gitlab-build-images:.*docker&patternType=regexp&case=yes
• https://sourcegraph.com/search?q=repo:gitlab.com/gitlab-com+registry.gitlab.com/gitlab-org/gitlab-build-images:.*docker&patternType=regexp&case=yes

User projects of these image are:

• https://gitlab.com/gitlab-org/gitlab-insights: deprecated
• https://gitlab.com/gitlab-com/people-group/peopleops-eng/assessment-tool: 🚧 gitlab-com/people-group/peopleops-eng/assessment-tool!98

so we can safe remove/deprecate these images.

Signed-off-by: Takuya Noguchi takninnovationresearch@gmail.com

Closes #70 (closed)