Update VTS test for the function `hardwareReset()`

The function `hardwareReset()` throws
`EX_UNSUPPORTED_OPERATION` if the Thread radio chip doesn't
support the hardware reset. Current VTS test assumes that the
Thread radio chip must support the hardware reset.

This CL updates the VTS test to verify the return value
`EX_UNSUPPORTED_OPERATION`.

bug: b/320393041
Test: run vts -m VtsHalThreadNetworkTargetTest
Change-Id: I7b0b2a4e850a1eda085a6d6c24cdd8aae6498aac