Fixup heap buffer overflow in cmd line args parsing unit tests

[dalg24]

Bug was introduced in #3459.

One argument was uninitialized which yielded an heap overflow caught by
the adress sanitizer.

[dalg24]

kokkos/core/unit_test/TestDefaultDeviceTypeInit.hpp

Line 70 in a7112b1

(do_other ? 4 : 0) + (do_tune ? 1 : 0);

and

kokkos/core/unit_test/TestDefaultDeviceTypeInit.hpp

Line 137 in a7112b1

sprintf(args_kokkos[device_idx + (do_device ? 1 : 0)], "dummy4arg=1");

indicate the intention of intercalating an "other" argument after the "device" one.