[repository] Drop type_and_source_from_eid and rename related cache
We don't want to handle anymore the entities.asource column so we shouldn't use
those anymore. Also rename repository's _type_source_cache into
_type_extid_cache as this is what it's containing now.
Do similar renaming to the system source API.
Related to #15538288
# re-read ComputedRelation permissions from schema.py now that we're
# able to serialize them
for computedrtype in schema.iter_computed_relations():
sync_schema_props_perms(computedrtype.type)