Would be nice to have option to set GCP template instead of setting all required variables in plugin configuration.

If template would be used only some options would be set in jenkins (like labels and timeouts)

That would allow to moving most of configuration related to instance into GCP where could be automatised using terraform or similar tools.

That would also allow to set some options that are now not available thru plugins like extra labels, use custom instances, or adding local SSD discs, or any other option that will be added to GCP. 

And if done correctly would simplify plugin a lot.