Vocab refresh: Update `networkx` graphs

[joeflack4]

addresses #977

Changes

DB Refresh: relationship_graph fix

• Update: When app starts and also every time home route is hit, it will now update relationship_graph if it is out of date.

General updates

• Codestyle and comment updates
• Moved some code that was causing PyCharm debugger to run tests inside of a non-test file.

Tests

• Bug fix: Updated GH action for tests in order to be able to access relationship_graph.pickle

[Sigfried]

@joeflack4, You got rid of some missing-in-between stuff, or just moved it. Yes -- it's not being used right now. I left the code in place in case we end up with problems where get_all_descendants is making the graph too big. It hasn't happened yet. Maybe we should just get rid of all missing-in-between code and leave a comment pointing to commit where it was last present in case we need to restore it someday.

In looking at it, I noticed that filled_gaps doesn't seem to appear in frontend code at all anymore. It does still appear in some test data.

[Sigfried]

I'm about to clean this all up.