Auto-cancel redundant builds on new commits

- Add workflow auto_cancel to cancel old pipelines
- Mark build job as interruptible
- Deploy jobs remain non-interruptible for safety

.gitlab-ci.yml

@@ -6,8 +6,13 @@ variables:
   DOCKER_BUILDKIT: 1
   CI_BUILDX_ARCHS: "linux/amd64"
 
+workflow:
+  auto_cancel:
+    on_new_commit: interruptible
+
 build:
   stage: build
+  interruptible: true
   image: docker:24
   services:
     - docker:24-dind