Don't run NonMovingAlloc operations by default in ThreadStress.

Allocations in the non-moving space fail the followin assertion
with the GSS collector:

  semi_space.cc:363] Check failed: kUseRememberedSet == rem_set != nullptr

Disable them while we investigate.

Test: art/test/testrunner/testrunner.py -t 004-ThreadStress
Bug: 72738921
Change-Id: I35e01ffc3e54af8e1f2e53b7aeb2add5a2ef4271