enable Gitlab backups

I am configuring gitlab backups via cron and the puppet module.

Here is a MR: https://share.riseup.net/#P2Yu4rpQubidQ0V5r7QM1Q

This does the following:

Configure gitlab backups via the puppet module. Will create a backup file every night at 2 am on /srv/backups It will use Gitlab backup command which is a wrapper of the rake task within gitlab rails. More information on: https://docs.gitlab.com/ee/raketasks/backup_restore.html#back-up-gitlab

It also set a cron job to backup gitlab secrets every night at 2 am and place it on /srv/backups.