Add more AO/CO test coverage which covers a fixed bug from v4.1.0.0. Also,
add some cardinality and domain tests on bitmap indexes and scans. Most of
these test additions are modified/inspired from Pivotal's internal testing.

Many of the test queries were doubled: run first within an ignore-block,
and then for real. That seems pointless, so remove the duplicates. Also,
fix typos in comments.

This hopefully fixes test failures that we've occasionally seen in the
buildfarm, where the mechanism in gpdiff.pl that masks out result set
ordering differences gets confused by the duplicated queries in the
ignore-blocks.