PIM-1718 : remove deprecated flexible config

The goal is to remove the useless flexible config, we can fulfill it by getting information from doctrine meta, with this change, we don't need to change many parameters when we want override the product, attribute, value, option or option value entities

 - remove flexible config
 - double check that scopable and localizable listeners are used

Bug fix: no
Feature addition: no
Backwards compatibility break: yes
Unit test passes: yes
Specs passes: yes
Replaced unit test classes removed: yes
Behat scenario passes: yes
Checkstyle issues: no
ChangeLog updated: yes
Fixes the following jira:
 - PIM-1718