Use Dockerfile based on vscode-linux-build-agent docker image

Description

• See details in tracking issue: Blocking: Replace Microsoft provided VSCode web... (gitlab-web-ide#12 - closed)
• Switches to usage of Dockerfile created in Create Dockerfile.gitlab-vscode-fork-node (gitlab-build-images!570 - merged)
• Adds logic to download and install node and yarn, and cache the download tarballs to avoid flaky builds due to failed downloads.

Image details

• https://gitlab.com/gitlab-org/gitlab-build-images/container_registry/131?orderBy=NAME&sort=asc&search[]=gitlab-vscode-nodeless&search[]=
• registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-vscode-nodeless