[dataimport] drop massive store etype to eid index and fix potential problem with is_instance_of relation insertion in case where the class of inserted entity has some (yams) parent.

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
https://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))