Convert radios on data retention page (basic)

app/main/forms.py

@@ -2097,14 +2097,14 @@ class BrandingOptions(StripWhitespaceForm):
 
 class ServiceDataRetentionForm(StripWhitespaceForm):
 
-    notification_type = RadioField(
+    notification_type = GovukRadiosField(
         'What notification type?',
         choices=[
             ('email', 'Email'),
             ('sms', 'SMS'),
             ('letter', 'Letter'),
         ],
-        validators=[DataRequired()],
+        thing='notification type',
     )
     days_of_retention = GovukIntegerField(
         label="Days of retention",

app/templates/views/service-settings/data-retention/add.html

@@ -2,7 +2,6 @@
 {% from "components/page-header.html" import page_header %}
 {% from "components/page-footer.html" import page_footer %}
 {% from "components/form.html" import form_wrapper %}
-{% from "components/radios.html" import radios %}
 
 {% block service_page_title %}
   Data retention
@@ -16,7 +15,7 @@
     ) }}
 
     {% call form_wrapper() %}
-      {{ radios(form.notification_type) }}
+      {{ form.notification_type }}
       {{ form.days_of_retention }}
       {{ page_footer('Add') }}
     {% endcall %}