[tests/checkintegrity] use the new connection api * serverctl: the db-check command also uses an internal connection object, which makes more sense in the context of `checkintegrity`. * checkintegrity: rename srvcnx to just cnx (a bit because in the near future, there will be one cnx to rule them all)

#!/usr/bin/env python
from cubicweb.cwctl import run
import sys
run(sys.argv[1:])