The result of NULL not in an unempty set is false. The result of
NULL not in an empty set is true. But if an unempty set has
partitioned locus. This set will be divided into several subsets.
Some subsets may be empty. Because NULL not in empty set equals
true. There will be some tuples that shouldn't exist in the result
set.

The patch disable the partitioned locus of inner table by removing
the join clause from the redistribution_clauses.

this commit cherry pick from 6X_STABLE 8c93db54f3d93a890493f6a6d532f841779a9188
Co-authored-by: NHubert Zhang <hubertzhang@apache.org>
Co-authored-by: NRichard Guo <riguo@pivotal.io>

These tests compare generated plans to catch significant plan changes
during subselect pull up for IN, EXISTS, NOT IN, NOT EXISTS related
queries.

There's no need to allocate ExecWorkFile struct in TopMemoryContext. We
don't rely on a callback to clean them up anymore, they will be closed
by the normal ResourceOwner and MemoryContext mechanisms. Otherwise,
the memory allocated for the struct is leaked on abort.

In the passing, make the error handling more robust.

Also modify tuplestorenew.c, to allocate everything in a MemoryContext,
rather than using gp_malloc() directly. ResourceOwner and MemoryContext
mechanisms will now take care of cleanup on abort, instead of the custom
end-of-xact callback.

Remove execWorkFile mock test. The only thing it tested was that
ExecWorkFile was allocated in TopMemoryContext. That didn't seem very
interesting to begin with, and the assumption is now false, anyway. We
could've changed the test to test that it's allocated in
CurrentMemoryContext instead, but I don't see the point.

Per report in private from Karthikeyan Rajaraman. Test cases also by him,
with some cleanup by me.

There is some overhead for every statement executed, so we can shave a few
seconds from regression tests by using multi-line INSERTS instead of
inserting each row in a separate statement.

Also remove some dummy SELECTs from heapscan1 test while we're at it.