ci: use PKG_BUILD_EXCLUDE to exclude some dists

.gitlab-ci.yml

@@ -3,15 +3,7 @@ include:
     file: 
       - 'templates/gitlab-ci-buildpkg.yml'
       - 'templates/gitlab-ci-buildpkg-host.yml'
+    ref: exclude
 
-.build-base:
+variables:
-  parallel:
+  PKG_BUILD_EXCLUDE: "/debian:(buster|bullseye)|ubuntu:(bionic|focal)/"
-    matrix:
-      - PKG_BUILD_IMAGE:
-          - ubuntu:impish
-          - ubuntu:jammy
-          - ubuntu:lunar
-          - ubuntu:mantic
-          - ubuntu:noble
-          - debian:bookworm
-          - debian:trixie