Update how we install Python packages in Docker

> The python error has an easy and a hard solution. For now I think we can try the easy but dangerous one and then we can consider the best way to implement the hard but safe one.
>
> Basically, we can force install the Python packages at the system level, which is what we are doing, but has always been a not-great idea.
>
> A longer term solution will be to install the packages in a separate environment and then update the skel files to direct all users to that environment. Let's file a separate issue to come back to that.

_Originally posted by @jashapiro in https://github.com/AlexsLemonade/training-modules/pull/884#pullrequestreview-3688369082_

This issue is a placeholder to track planning/implementing a longer-term more robust solution.

Start by reviewing how Python packages are installed in the Docker setup and how the skel files direct users to the environment. Define a separate package environment and update those user directions, then verify that package installation and user access work without system-level installation.

Written by the indexing model from the issue text.