Pull Request for Issue #16574.

Summary of Changes

When a "Contact - Mail" custom field is assigned to a category, then on the front only the fields in the contact form should be shown where the actual contact belongs to.

Testing Instructions

• Create a contact category A
• Create a contact category B
• Create a contact A for category A
• Create a contact B for category B
• Create a Mail custom field with the title A and assign it to category A
• Create a Mail custom field with the title B and assign it to category B
• Create a menu item for contact A
• Create a menu item for contact B

Expected result

• When opening contact A on the front only the custom field A should be shown below the contact form.
• When opening contact B on the front only the custom field B should be shown below the contact form.

Actual result

• When opening contact A on the front the custom field A and B are shown below the contact form.
• When opening contact B on the front the custom field A and B are shown below the contact form.