obs: only link Fedora images in PRs

This is enough to set up the repositories if needed for PRs,
no need to waste more resources

.obs/workflows.yml

@@ -15,22 +15,10 @@ ci:
         source_package: systemd
         target_project: system:systemd:ci
     # Also prepare some images, but disabled by default to avoid wasting cpu/disk
-    - link_package:
-        source_project: system:systemd
-        source_package: particleos-debian
-        target_project: system:systemd:ci
-    - link_package:
-        source_project: system:systemd
-        source_package: particleos-debian-arm
-        target_project: system:systemd:ci
     - link_package:
         source_project: system:systemd
         source_package: particleos-fedora
         target_project: system:systemd:ci
-    - link_package:
-        source_project: system:systemd
-        source_package: uki-debian
-        target_project: system:systemd:ci
     - link_package:
         source_project: system:systemd
         source_package: uki-fedora