[schema] fix pb with ambiguous relation used within UniqueTogetherConstraint by having CWUniqueTogetherConstraint.relation targeting CWRType instead of CWAttribute/CWRelation. This fixes 3.10.7 migration.

if 'same_as' in schema:
    sync_schema_props_perms('same_as', syncperms=False)
sync_schema_props_perms('Bookmark', syncperms=False)