[entities, view] delete dead code
The auto_unwrap_bw_compat metaclass calls unwrap_adapter_compat, which
was removed in changeset 697a8181ba30 "remove 3.9 bw compat". So this
can't possibly work anymore, meaning we can get rid of it.
change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')