Remove DiskStat checks from VTS Health HAL test

The fields being checked were uint64_t and it
is valid for them to have any value greater than
or equal to zero.

Bug: 74057048
Test: vts-tradefed run vts -m VtsHalHealthV2_0
Change-Id: If932e1d6af8e162b7c570a1d5dd0f5ddce89ad1e