Fix testing logic in tests/testing/asserters_test.py

[ajpotts]

Here is an example where the logic is not quite right:

        with pytest.raises(AssertionError):
            if both_ak:
                assert_arkouda_array_equal(c, c2)
            assert_arkouda_array_equivalent(convert_left(c), convert_right(c2))

In this case, the second assert will not execute when both_ak=True. This ticket is to fix the issue throughout the file.