fix: include catalog_visibility filter in courseware_content

The catalog_visibility filter is passed to the courseware_content index
when performing a search using the legacy student dashboard view. If not
included an error like follows is raised:

    MeilisearchApiError. Error code: invalid_search_filter. Error message:
    Attribute `catalog_visibility` is not filterable

search/meilisearch.py

@@ -104,6 +104,7 @@
         PRIMARY_KEY_FIELD_NAME,  # exclude some specific documents based on ID
         "course",  # search courseware content by course
         "org",  # used during indexing
+        "catalog_visibility",  # exclude visibility="none"
         "start_date",  # limit search to started courses
     ],
 }