Most of time is spent on running the 4 minidumps in CalibratedCostModel test.
The 4 minidumps are already tested in other test suites. Moreover, it just
executes the minidump, doesn't even compare the generaeted plan.

CalibratedCostModel is default in GPDB right now, and most minidumps use
calibrated cost model, that will also test CalibratedCostModel at the same
time. So remove EresUnittest_CalibratedCostModel. Cut down the debug runtime
of CCostTest from 814829 ms to 458 ms.