In the process of working on CXX-2577 it became apparent that the valgrind tests were unexpectedly failing and in such a way that was not possible to effectively remedy. In particular, the change to a more up-to-date CMake resulted in the valgrind tasks failing consistently. This suggests that different compiler flags might be involved in the failure. However, the failures being observed are all outside of the C++ driver and valgrind is indicating that is "confused" by the situation.

Since valgrind tasks were removed from the C driver already (CDRIVER-3620), they don't seem to be providing any benefit, and since the C++ driver still has an entirely separate group of ASAN and UBSAN tasks, the valgrind tasks ought to be removed.