Merge branch 'use-kubernetes-runner' into 'master'

Migrate to Kubernetes for tests

This will change the build_branch and lint steps to be executed on the Kubernetes cluster in Azure (see https://gitlab.com/gitlab-com/infrastructure/issues/749 for the whole story). This is anticipated to save us significant bandwidth charges!

I've scheduled discussion of this on the Monday team call.

See merge request !4284
4 jobs for lm-update-handbook-support-security-process in 4 minutes and 35 seconds (queued for 2 seconds)