Add infrastructure for Cloud VPS test system

[lucaswerkmeister]

This adds an Ansible playbook and related files for automatically setting up a WikibaseReconcileEdit test system on Wikimedia Cloud VPS. The setup is largely based on that of WikibaseManifest; significant differences include:

• We target MediaWiki and Wikibase 1.35, not master. Consequently, Wikibase is loaded using the PHP entry points.
• The instance hostname is changed from .eqiad.wmflabs to .eqiad1.wikimedia.cloud, and the domain name from .wmflabs.org to .wmcloud.org.
• The wiki does not allow anonymous editing nor registration. Use createAndPromote.php to create initial accounts.
• The script path is /w, and the article path is /wiki/$1; for the script path, /var/www/html/w is set up as a symlink to /var/www/html, as in WikibaseManifest, but we do it inside setup.yml rather than in the Dockerfile, because any /var/www/html modifications in the Dockerfile get lost when docker-compose mounts a different directory over /var/www/html.
• Several tasks in setup.yml are moved to pre_tasks; this is necessary to ensure that the SCRIPTS_DIR exists by the time the git_updater role runs, which uses that directory.
• The Query Service setup is removed, since we don’t need it and it requires a lot of RAM.
• WikibaseImport is removed, since we don’t need it.

Bug: T282230

[lucaswerkmeister]

Pushed a new version with /w + /wiki support.