[libc][math][c23] Fix totalorder and totalordermag smoke tests (#100354)
FPBits::signaling_nan() defaults to setting the MSB of the payload to 1.
The tests also used signaling NaNs with a payload of 0x123. With
float16, the 1 in 0x123 aligns to the MSB of the payload, therefore
0x123 is greater than the default payload. However, that is not the case
with more precise floating-point types.