tests/functional: Switch back to the gitlab URLs for the advent calendar tests

Shortly after we switched to the original URLs on qemu-advent-calendar.org,
the server went offline - looks like we are better off using the gitlab
URLs again instead.

Message-ID: <20241007083649.204886-1-thuth@redhat.com>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
8 files changed