Update backup object

Fixes: https://gitlab.com/charts/gitlab/issues/1036

• Update our backup used in the tests to today's master to workaround an model issue when restoring repos
• Set the runner token after restoring the backup, in order get around the fact that we haven't restored the db encryption secrets, and as a result can't read the token from the backup. (See: https://gitlab.com/gitlab-org/gitlab-ce/issues/55596)
• Collect the screenshots we produce during the run as artifacts on failure