build: Fixup GCB configs for debian-{base,iptables} images

- Fix dir arguments
- Drop 'BASE_REGISTRY' env var from debian-iptables config

Signed-off-by: Stephen Augustus <[email protected]>

Author: justaugustus

build/debian-base/cloudbuild.yaml

@@ -6,6 +6,7 @@ options:
 steps:
   - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20200422-b25d964'
     entrypoint: make
+    dir: ./build/debian-base
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
       - REGISTRY=gcr.io/$PROJECT_ID

build/debian-iptables/cloudbuild.yaml

@@ -6,10 +6,10 @@ options:
 steps:
   - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20200422-b25d964'
     entrypoint: make
+    dir: ./build/debian-iptables
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
       - REGISTRY=gcr.io/$PROJECT_ID
-      - BASE_REGISTRY=gcr.io/$PROJECT_ID
       - IMAGE=gcr.io/$PROJECT_ID/debian-iptables
     args:
       - all-push