UI form slug field value changes every time the name is updated

[abhi1693]

NetBox version

v3.2.6

Python version

3.10

Steps to Reproduce

1. Create a contact role (End User) with slug (end-user-1)
2. Edit the same role and change the name to Customers
3. Notice the slug field gets changed

Expected Behavior

The slug field should only change when it is empty

Observed Behavior

The slug field always updates

[abhi1693]

To add more context, this issue is on every form there is a slug field. We use slug fields in automation rules and do not expect these to change once these are set. However, sometimes there is a need to update the name field but not change the slugs to avoid breaking our automation workflows.

[jeremystretch]

This is a regression of #3810 apparently introduced in v3.0.