[devtools] properly close open access on tearDown avoiding further warning about living sessions while the repo is turned off. The doc string says: The RepoAccess need to be closed to destroy the associated Session. TestCase usually take care of this aspect for the user. but that wasn't true until now.

rql('SET X name "BoundaryConstraint" '
    'WHERE X is CWConstraintType, X name "BoundConstraint"')