Collapsing Metadata section when creating or features deletes all unsaved changes

### How are you running Flagsmith

- [ ] Self Hosted with Docker
- [ ] Self Hosted with Kubernetes
- [X] SaaS at flagsmith.com
- [ ] Some other way (add details in description below)

### Describe the bug

The Metadata section shown when editing or creating features is collapsible. If changes are made to fields in that section and it's collapsed without saving changes, those changes are permanently lost.

### Steps To Reproduce

1. Create a metadata field for features
2. Create a new feature and open the Metadata section
3. Type something into a metadata field
4. Collapse the Metadata section

Your changes are now gone.

### Expected behavior

Never delete unsaved user data when editing custom fields.

My strong preference would be to remove the collapsible section altogether, and don't show it if no metadata fields are configured. Metadata fields should have the same prominence/visibility as regular fields - we can't assume anything about how important they should be to customers.

Hiding required fields behind a collapsible section or a different tab and not highlighting them in any way is also a surefire way to frustrate users.

### Screenshots

https://github.com/Flagsmith/flagsmith/assets/829698/ad004e51-b687-4e9e-9e14-f793f4671c78