🔥(edxapp) remove legacy edxapp_sql_dump_url var

This is a follow up of the hawthorn upgrade (see c52ed36), loading an
SQL dump is no longer required, hence this legacy variable should be
removed.

Author: jmaupetit

apps/edxapp/vars/all/main.yml

@@ -8,7 +8,6 @@ edxapp_lms_host: "lms.{{ project_name}}.{{ domain_name }}"
 edxapp_image_name: "fundocker/edxapp"
 edxapp_image_tag: "hawthorn.1-1.0.0"
 edxapp_django_port: 8000
-edxapp_sql_dump_url: "https://gist.github.com/jmaupetit/1f9d270d7d2106774fd94ba89a51ab78/raw/b0004f2825623d03de58710bf936db175e96bc90/edx-database-ginko.sql"
 
 # -- memcached
 edxapp_memcached_image_name: memcached