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Fix flaky GPU/CPU timestamp duration comparison in cmd-query tests (#775)

The cmd-query-resolve-host and cmd-query-resolve-device tests assert
CHECK(durationGPU < durationCPU), comparing the span of GPU timestamp
queries against the CPU wall-clock time of the enclosing loop. The CPU
interval is meant to bound the GPU span, but durationCPU is truncated to
whole microseconds and a fast loop (notably the macOS release runners)
spans only a few microseconds, so the sub-microsecond containment margin
can vanish and the strict comparison flips intermittently (observed as 1
failing assertion in ~10.4M).

Loosen the comparison to <= with a tolerance covering integer-microsecond
truncation, cross-clock jitter, and the GPU's own timestamp granularity
(2 / timestampFrequency, which dominates on coarse-timer backends). This
keeps the magnitude/units sanity-check while removing the race; timestamp
monotonicity is still asserted separately and is unchanged.

Co-authored-by: nv-slang-bot[bot] <274397474+nv-slang-bot[bot]@users.noreply.github.com>
Co-authored-by: Harsh Aggarwal <haaggarwal@nvidia.com>
Co-authored-by: Simon Kallweit <64953474+skallweitNV@users.noreply.github.com>

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