Can't remove custom rate limit entries from user form #306
Description
If an API user is added with custom rate limits, you can't remove individual custom rate limits from the table by editing the record. You can click the "Remove" button next to an individual limit and after confirming removal, it disappears from the interface, but after saving the record, the removed entires are still present after reloading.
Oddly, the removal action does work on the custom rate limits defined on API Backends, it's just on the API Users from where this is broken. There were some subtle differences in edits due to #303, but with that fixed, I'm not quite sure what's causing the differences in behavior between the two forms since they both use the same underlying Settings model. Need to investigate more, but it seems to be something more related to the model setup and the Rails accepts_nested_attributes_for behavior.