revert: "build(woodpecker): remove redundant build of a builder images"

This reverts commit 38f236fc37.

.woodpecker/cron-docker-builder.yml

@@ -0,0 +1,15 @@
+steps:
+
+  update-builder-image:
+    when:
+      - event: cron
+    image: docker.io/woodpeckerci/plugin-docker-buildx:latest
+    settings:
+      username: kemitix
+      repo: git.kemitix.net/kemitix/git-next-builder
+      auto_tag: true
+      dockerfile: Dockerfile.builder
+      dry-run: false # push to remote repo
+      registry: git.kemitix.net
+      password:
+        from_secret: woodpecker-docker-push