[Admin] Show error message when trying to delete an active shipping method

[audez]

Description

On the shipping method list page (admin/shipping_methods), you can delete an active shipping method. It will disappear from the page as if it was deleted, but in fact it was not.

Expected Behavior

If an active shipping method can't be deleted:
Grey out the Trash icon (and display a message on hover)
or
Show an error message when clicking on the trash icon to delete the method, for ex "You can't delete an active shipping method. Please first disable this method in your enterprise setting."

Actual Behaviour

You can click on the trash to delete an active shipping method. The method will disappear from the page and user thinks it was deleted, but it was not. It still appears as an active method in the Enterprise settings.

Steps to Reproduce

1. Go to Enteprise > Settings > Shipping methods
2. Activate two shipping methods
3. Click on "Edit" on one of the shipping methods, then "Back to shipping method list"
4. Click on the trash for one of the active shipping methods. It will be deleted from the list.
5. Refresh the page and see it again.

Animated Gif/Screenshot

1 - "tet" is an active method. I can delete it

2 - it is removed from the list without error

3 - after refreshing the page, it appears again

Workaround

Disable the shipping method in your enterprise setting before deleting it.

Severity

bug-s4: it's annoying, but you can use it

[audez]

Actually it applies only if the shipment method has been used in an order so it's a duplicate of #6135