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* Add USE_ENTERPRISE_CATALOG waffle sample, and remove USE_ENTERPRISE_CATALOG waffle flag
* Switch the use of waffle.flag_is_active to waffle.sample_is_active
* Updates the EnterpriseCatalogApiClient to make the user argument optional. If the user argument is not provided, it will use the "enterprise_worker" user instead
* No longer passes user to the EnterpriseCatalogApiClient during initialization in places where a request and/or user object doesn't already exist