Remove template type parameter on redirect

This is a hangover from when we had separate email/SMS template pages.
If the view doesn’t use a parameter Flask adds it to the querystring. So
we were getting URLs that ended in `?template_type=sms`, to no effect.

app/main/views/templates.py

@@ -347,7 +347,6 @@ def delete_service_template(service_id, template_id):
         return redirect(url_for(
             '.choose_template',
             service_id=service_id,
-            template_type=template['template_type']
         ))
 
     try: