test(promql): some functions silently ignore native histograms

Functions that silently ignore native histograms, not covered by existing
tests: abs(), ceil(), clamp(), clamp_min(), clamp_max(), floor(), round().

Ref: https://github.com/prometheus/prometheus/pull/15845



Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>