gitlab-ci: use kaniko debug-arm64 build from our own container registry

.gitlab-ci.yml

 build:
   stage: build
   image:
-    name: gcr.io/kaniko-project/executor:arm64
+    name: source.mnt.re:5050/reform/build-kaniko-arm64-docker
     entrypoint: [""]
   script:
     - mkdir -p /kaniko/.docker