[server] move security/integrity hook management away from InternalSession.__init__
and to Repository.internal_{session,cnx} instead. Lets internal_cnx avoid
deprecation warnings.
if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
ask_confirm=False):
rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
ask_confirm=False)