Formatting changes for gmp-bot comment

[Adib234]

gmp-bot comment wasn't formatted correctly because of templating issues as shown here https://screenshot.googleplex.com/AeZQqDCg5qhh5J7.png, this change makes sure that the code block is formatted multi-line instead of single line

I used Heredoc to verify

adibakm@adib9:~/prometheus-test-infra$ cat << EOF
\```\```\```gcloud container clusters get-credentials prombench --zone us-east4-a --project gpe-test-1\n kubectl config use-context gke_gpe-test-1_us-e
ast4-a_prombench\n kubectl port-forward services/parca 31802:80\```\```\``` 
EOF
```gcloud container clusters get-credentials prombench --zone us-east4-a --project gpe-test-1\n kubectl config use-context gke_gpe-test-1_us-east4-a_prombench\n kubectl port-forward services/parca 31802:80```