chore: Migrate gsutil usage to gcloud storage (#2705)

Co-authored-by: Anthonios Partheniou <partheniou@google.com>

Author: gurusai-voleti

samples/compute/startup-script.sh

@@ -31,10 +31,10 @@ wget $IMAGE_URL
 convert * -pointsize 30 -fill white -stroke black -gravity center -annotate +10+40 "$TEXT" output.png
 
 # Create a Google Cloud Storage bucket.
-gsutil mb gs://$CS_BUCKET
+gcloud storage buckets create gs://$CS_BUCKET
 
 # Store the image in the Google Cloud Storage bucket and allow all users
 # to read it.
-gsutil cp -a public-read output.png gs://$CS_BUCKET/output.png
+gcloud storage cp --predefined-acl=public-read output.png gs://$CS_BUCKET/output.png
 
 # [END compute_apiary_startup_script]