Answering my own question, in case it helps someone else.
When click on "open a cloudshell" in your Google Cloud VM window for your SuiteCRM Bitnami instance, it launches a shell to another VM, and you are not in the SuiteCRM machine. You have to click on the "SSH" button to get a shell on the SuiteCRM machine.
The application root is here: /opt/bitnami/apps/suitecrm/
The config.php and config_override.php files are here: /opt/bitnami/apps/suitecrm/htdocs/