cloudbuild.yaml: decrease timeout to 25 minutes

Build time decreased dramatically after upgrading the builder machine
type.

cloudbuild.yaml

@@ -1,4 +1,4 @@
-timeout: 4800s
+timeout: 1500s
 steps:
   - name: gcr.io/k8s-staging-test-infra/gcb-docker-gcloud:v20211118-2f2d816b90
     entrypoint: scripts/test-infra/push-image.sh

scripts/test-infra/test-e2e.sh

@@ -19,11 +19,11 @@ i=1
 while true; do
     if make poll-images; then
         break
-    elif [ $i -ge 50 ]; then
+    elif [ $i -ge 27 ]; then
         echo "ERROR: too many tries when polling for image"
         exit 1
     fi
-    sleep 100
+    sleep 60
 
     i=$(( $i + 1 ))
 done