Use old kaniko executor for now.

dancerj · dancerj · commit 45c2dd53a048 · 2021-10-22T14:42:30.000+09:00
From GoogleContainerTools/kaniko#1242
diff --git a/cloudbuild.yaml b/cloudbuild.yaml
@@ -1,5 +1,5 @@
 steps:
-- name: 'gcr.io/kaniko-project/executor:latest'
+- name: 'gcr.io/kaniko-project/executor:v1.6.0'
   args:
     - --destination=gcr.io/$PROJECT_ID/gitlstreefsbuilder
     - --cache=true
