[general] dataproc clusters incompatible with apt-key add deprecation

[cjac]

Since Debian has begun enforcing the warning it has been issuing related to loading repo-specific trust keys into the root trust, dataproc has not been able to make use of any of the apt-get commands.

This issue needs to be addressed with a new build of the base image, but until this happens, there is a workaround at the footer of gpu/install_gpu_drivers.sh