Use client_request fixture where possible

It:
- saves repetetive boilerplate code
- does some extra checks (eg checking for a `200` response)
- makes the codebase less confusing to consistently do the same thing in
  the same way

app/templates/views/service-settings/set-auth-type.html

@@ -3,7 +3,7 @@
 {% from "components/page-footer.html" import page_footer %}
 
 {% block service_page_title %}
-  Text message sender
+  Sign-in method
 {% endblock %}
 
 {% block maincolumn_content %}

app/templates/views/templates/action_blocked.html

@@ -3,7 +3,7 @@
 {% from "components/page-footer.html" import page_footer %}
 
 {% block service_page_title %}
-  Emails
+  {{ notification_type.capitalize() }} are disabled
 {% endblock %}
 
 {% block maincolumn_content %}