CI: Switch to plain Alpine image with modern ansible-lint

This also enables GitLab-parseable ansible-lint output.

Cf. common!26 (merged)

This also removes two unsupported and obsolete roles, as well as fixing a few (minor) issues along the way.

pyxtrlock/handlers/main.yml

----
-
-- name: remove pyxtrlock mouse symbol
-  command: ../bin/python make_empty_lock.py
-  args:
-    chdir: /opt/pyxtrlock/pyxtrlock
-
-- name: setup pyxtrlock
-  command: ../bin/python setup.py install
-  args:
-    chdir: /opt/pyxtrlock/pyxtrlock