[repo] more efficient eid cache operations handling based on set_operation; refactor
* split CleanupEidTypeCache operation into one operation for deleted eids
and another for added eids, and put them in cw.server.hook
* for consistency, move fti unindexing handling from the repository
to the system source
* handling of deleted eids is done in plan execution (ssplanner), no
needs to redo it in *delete_info
-> no more need for _prepare_delete_info method, killed