startup script needs to install java in some cases

It looks like this installation: https://github.com/DataBiosphere/terra-cli/blob/0.46.0/notebooks/post-startup.sh#L39
is not happening correctly on TF-based images and containers, since java is not installed.  (https://bit.googleplex.com/#/amyu/6347257634881536).  Probably the startup script needs to be modified to do that if it's not already installed.