Event state remains as scheduled when changing visibility to 'not visible or scheduled'

[a-jaxell]

Description

This was briefly mentioned in #2005 (comment)

The Event state is not set correctly when setting and unsetting visibility date.

Steps to reproduce

1. Go to https://app.dev.zetkin.org/organize/1/projects/
2. Click on any project
3. Create an event draft
4. Set visibility to a future date
5. Click outside the date picker
6. Open the date picker and press x to clear the date
7. Click outside the datepicker

Expected Behaviour

Event state should change to default draft state

Actual Behaviour

Event state remains as scheduled

Screenshots (if you have any)

Screen.Recording.2024-10-14.at.20.52.43.mov

[helihard]

I think I have located the error in the code, will PR a suggested solution later today.