Hitting maximum usage limits in Cloud Shell, service unavailable
Solution 1:
Google offers Container-Optimized OS which is optimized to run Docker containers however this is still in Beta phase. More information about it can be found in this Help Center article.
However, for the Cloud Shell usage limits, as Carlos mentioned in the comment the following documentation explains the usage limits but doesn't provide specific threshold and if your session is terminated or cannot be established because you exceeded a service limit, Cloud Shell will display an error with a link to a form that allows you to appeal the limit violation. Click the feedback link and submit the form with more information about the tasks you were performing before your session was terminated.