Summary:
Allow expressions for variable length path bounds
Replace test which expected a syntax exception
Since we now allow variable length to have an arbitrary expression, the
test case is obsolete. It was replaced with something that excepts an
expression which wasn't allowed before.
Reviewers: florijan, mislav.bradac, buda
Reviewed By: mislav.bradac
Subscribers: lion, pullbot
Differential Revision: https://phabricator.memgraph.io/D568