After #33507, the jupyter kernel sagemath gets invoked during the docbuild.
This can lead to a new class of errors as seen in #33507 comment:75 and #33507 comment:86

We fix it by setting JUPYTER_DATA_DIR and JUPYTER_PATH during the docbuild so that a random broken user configuration of Jupyter in ~/.jupyter does not break the docbuild.

See https://docs.jupyter.org/en/latest/use/jupyter-directories.html#configuration-files

CC: @kwankyu @dimpase @collares

Component: documentation

Author: Matthias Koeppe

Branch: 614822c

Reviewer: Kwankyu Lee

Issue created by migration from https://trac.sagemath.org/ticket/33650