Move to GitLab CI

WTF I just checked that RedirectResponse contains "/admin/group/sites/settings", which works when running tests locally and somehow fails on Drupal CI. Gonna try and trigger this another way.

Okay so that works, asking around what changed in core that would explain the test failures on GitLab CI.

GitLab CI might run in subdirectories, leading the the failures we saw here.

How did this get set back to active? o.O

Automatically closed - issue fixed for 2 weeks with no activity.