Bug 433863 - s390x: Remove memcheck test cases for cs, cds, and csg

Bug 433863 - s390x: Remove memcheck test cases for cs, cds, and csg

The fix for bug 429864 - "s390x: C++ atomic test_and_set yields
false-positive memcheck diagnostics" changes the memcheck behavior at
various compare-and-swap instructions.  The comparison between the old and
expected value now always yields a defined result, even if the input
values are (partially) undefined.  However, some existing test cases
explicitly verify that memcheck complains about the use of uninitialised
values here.  These test cases are no longer valid.  Remove them.