Variants are no longer run automatically

From now on, all "non-current" variants in pipelines will default to manual triggering unless indicated otherwise. This should not affect the overall result of the pipelines, and the version set as "current" will continue to run automatically.

With this change, we are aiming to reduce the amount of CI minutes used on our instance of GitLab, which runs on AWS servers, and for which the Drupal Association pays.

This change affects all pipelines, regardless of how they are triggered.

The variants allowed in the default GitLab templates are a tool to spot-check whether a contributed project is fully compatible and runs well with other versions of Drupal (minor and major) or other versions of PHP. It should not be used for all types of changes (eg: fixing a typo, changing a field, etc) on a general basis.

There is a new set of variables to control this behaviour, which can be checked in the variants page.