Use graph groups to filter out ontology results

Virtuoso has this concept of graph groups. We have added all the
ontology graphs + ontology metadata graphs + virtuoso data graph in this
graph group.

All search results generated by the query engine do not contain results
from this graph. This is a much faster approach than the earlier user
visibility approach which would cause a huge performance bottleneck.

While the current approach is great. It still doesn't solve all our
problems. We still get graph results in the negated terms, and we STILL
get some ontology results in some queries. Probably a virtuoso bug.

REVIEW: 106878