Rewrite the banner to be less clunky

I think it had too many words before, and it wasn’t gramatically correct
in the singular case.

Author: quis

app/main/views/templates.py

@@ -775,8 +775,10 @@ def edit_service_template(service_id, template_id, language=None):  # noqa
                 template.template_type == "letter" and template.welsh_page_count and language != "welsh"
             )
             if template_change.email_files_removed:
+                multiple_files_removed = len(template_change.email_filenames_removed) > 1
                 flash(
-                    f"Files for {formatted_list(template_change.email_filenames_removed)} have been removed from the template.",  # noqa
+                    f"{formatted_list(template_change.email_filenames_removed)} "
+                    f"{'have' if multiple_files_removed else 'has'} been removed",
                     "default_with_tick",
                 )
             return redirect(

tests/app/main/views/test_templates.py

@@ -3760,14 +3760,14 @@ def test_should_redirect_when_saving_a_template_email(
                 "00000000-0000-4000-8000-000000000001",
                 "00000000-0000-4000-8000-000000000002",
             ],
-            "Files for ‘invite.pdf’ and ‘form.pdf’ have been removed from the template.",
+            "‘invite.pdf’ and ‘form.pdf’ have been removed",
         ),
         (
             "For the appointment, you will just need ((form.pdf)) and ((map.pdf))",
             [
                 "00000000-0000-4000-8000-000000000001",
             ],
-            "Files for ‘invite.pdf’ have been removed from the template.",
+            "‘invite.pdf’ has been removed",
         ),
     ),
 )