Remove CI from stable branch again

itinerary is part of PIM but has a more unusual set of deps. I'll have to
test this in a merge request first...

.gitlab-ci.yml

-# SPDX-FileCopyrightText: None
-# SPDX-License-Identifier: CC0-1.0
-
-include:
-  - https://invent.kde.org/sysadmin/ci-utilities/raw/master/gitlab-templates/android.yml
-  - https://invent.kde.org/sysadmin/ci-utilities/raw/master/gitlab-templates/linux.yml
-  - https://invent.kde.org/sysadmin/ci-utilities/raw/master/gitlab-templates/freebsd.yml