Fix my_related_object_list field on Base_viewMetadata, which accessed all related ZODB objects to display itself (which can lead to long transaction).
Instead, use a listbox with portal_catalog, which will only access displayed objects on the page.

Base_getRelatedObjectList was an unused script, so, no need to keep compatibility.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@28168 20353a03-c40f-0410-a6d1-a30d3c3de9de