Remove the visibility settings in the Coupon section.

### Reproduction Steps

1. Navigate to your WordPress dashboard.
2. Go to _Orders > Coupons_ or _Orders > Vouchers_
3. Click **Add New**
4. Locate the section in this screenshot: [link to screenshot](https://share.zight.com/v1u96qvk).

### Expected Behavior

The visibility section isn't visible

### Actual Behavior

The visibility section is visible, which has some unexpected results if changed.

1. When set to "public" or "password protected," the coupon is accessible to students. However, with "password protected," it doesn't prompt for a password entry same on public.

2. When set to "private," neither students nor instructors can use the coupon, only administrators and editors have access

Work the same with pages.

This issue has be recreated:
+ [ ] Locally
+ [ ] On a staging site