cubicweb #15538288 kill 'asource' and 'extid' columns from the 'entities' system table [validation pending]

both information are (or should be) available by other means (cw_source for asource, cwuri for extid).

Both entries (and related indexes) have heavy cost for cubicweb application handling millions of entity. They shouldn't pay that price when other options are available.

done in3.24.0
load left0.000
closed by#054a947b5415 [repository] Drop the entities.asource column
patch[entity] Reimplement and deprecate entity.cw_metainformation [applied][repository] Drop the entities.asource column [applied][integrity check] Stop using entities.asource column in integrity checks [applied][repository] Drop type_and_source_from_eid and rename related cache [applied][entity] Stop returning source information in cw_metainformation() [applied][json] Stop serializing cw_source into default json representation of an entity [applied][entity] Stop linking to external site for external entities [applied][datafeed] Drop entity deletion handling in the default source / parser [applied][repository] Drop deprecated extid2eid API and friends [applied][ldap] Stop using entities table in ldap source authentication and parser [applied]