I guess I would need to put this in the extra_vm_bash_script param of the auto-scaler, but it will reboot in loop right? Isn’t there an easier way to achieve that?

You can edit the extra_vm_bash_script which means the next time the instance is booted you will have the bash script executed,
In the meantime, you can ssh to the running instance and change the ulimit manually, wdyt?