Fix page titles that didn’t get fixed before

Did most of this work in:
https://github.com/alphagov/notifications-admin/pull/1118

> In pages specific to a service (e.g. dashboard and sub pages) the
> title needs to distinguish which service it applies to. This is mainly
> to give context to screen reader users who could be managing multiple
> services.
>
> Implementing this uses template inheritance:
>
> `page_title` includes `per_page_title` includes `service_page_title`
>
> ‘GOV.UK Notify’ is inserted into every page title.
>
> Pages that set `service_page_title` get the service name inserted too.

app/templates/views/user-profile/authenticate.html

@@ -2,8 +2,8 @@
 {% from "components/textbox.html" import textbox %}
 {% from "components/page-footer.html" import page_footer %}
 
-{% block page_title %}
-GOV.UK Notify | Service settings
+{% block per_page_title %}
+  Change your {{ thing }}
 {% endblock %}
 
 {% block maincolumn_content %}