(legacy) change behaviour of associated nat rules (https://github.com/opnsense/core/issues/695), show rule but hide edit and duplicate buttons

If for some reason a config has "typeless" rules, which don't belong to any active nat rule the user won't notice this anymore (and doesn't have the ability to remove them).
This can happen with imports from old configs for example or manually changed configs.

(cherry picked from commit e1dd1839)