Revisit path computation in optical path provisioner

apps/newoptical/src/main/java/org/onosproject/newoptical/OpticalPathProvisioner.java Line 681:
We may need to revisit this later.
We had to add this kind of constraint due to the fact,
current path computation service only gives us "only" the shortest paths and you can specify only specify nodes not ports.
So we had to exclude them in order to get a multi-layer path between same node pairs, but with different port pair.
Once we expose k-shortest path API, we should remove this extra negative constraint.

See here for original comment and patch:
https://gerrit.onosproject.org/#/c/13200