Yet more test changes to prepare for the hypergraph optimizer.

The biggest changes this time around comes from the fact that we open up
for optimizer trace; earlier, the hypergraph optimizer would refuse all
SELECTs involving optimizer trace, but now that it has its own (hopefully
useful) trace, the user should be allowed to query for it. Thus, the tests
involving optimizer trace need to skip it themselves.

Change-Id: I74414cddefe940f41134054080da779e39e27150