Separate prolog and sparql query phases in the events test.
Separate prolog and sparql query phases in the events test.

Expand the query phase into two phases, one for sparql queries, one
for prolog. Initialization of the workers for each phase still occurs
prior to the first of these phases.

make test-suite run? no

release notes: non-user-visible code change

Change-Id: Ia575f92effd2f6f995ef34ea0a6220afd241b65e

franzinc/agraph-python,franzinc/agraph-python,franzinc/agraph-python,franzinc/agraph-python