Drop deprecated LDAP related script
both are relying on the 'entities.source' column which has been dropped in 3.19.
They have been written with the old ldapsource in mind, which has been dropped at
that time.
[entity] Stop linking to external site for external entities
This behaviour was ok when we had "true" multi-sources but its rather painful
with datafeed sources. Also, it makes absolute_url() costlier than what it
should. Besides, it relies on cw_metainformation()['source'] that is pending for
removal.
Instead, add a link to the original object in the metadata view (the one that
displays eid and source at the bottom right corner of the primary view).
Related to #15538288.