charmed-spark-jupyter loses data on restart in Kubeflow

[gustavosr98]

By default in Kubeflow PVC mount point is at /home/joyvan which is also the same path where files are uploaded from the GUI
However, this image uploads files to /var/lib/spark/notebook, which is not the default PVC mount point for Kubeflow

If you stop and start again your Jupyter Notebook you will lose any files (including notebooks) created during your session

We should

1. Workaround (not ideal), document it so at least users when creating the notebook point to the right path
2. Have a way to configure default /home/joyvan path used in Kubeflow.
3. or a way to default link path /var/lib/spark/notebook with /home/joyvan in case the user forgets to change the mount point when creating the notebook (Which will most probably happen, even if we document it)

[github-actions]

https://warthogs.atlassian.net/browse/DPE-7975