CI: use standard docker for pkg:arch

Arch LXC images currently don't work :(

Standard docker can't test systemd but it's better than nothing.

.gitlab-ci.yml

@@ -688,10 +688,15 @@ pkg:alma-9:
 
 pkg:arch:
   <<: *pkg_test_user
-  image: $CI_REGISTRY/packaging/apkg/full/arch
-  allow_failure: true  # our image not starting up currently
+  image: $CI_REGISTRY/packaging/apkg/test/arch
+  tags:
+    - docker
+    - linux
+    - amd64
+  allow_failure: true  # our LXC image not starting up currently
   before_script:
     - pacman -Syy
+    - pip install apkg
 
 # RHEL 8 derivatives would need more work due to *default* python being old
 #pkg:rocky-8: