Some test queries need their interval adjusted to account for
https://github.com/prometheus/prometheus/pull/13904. Otherwise the
queries don't return enough samples.
promql/engine_test.go:TestHistogramCopyFromIteratorRegression needed the
same, but also the result needed a fix since `increase` interpolates
over the full range.
Signed-off-by: Jan Fajerski <jfajersk@redhat.com>
Same idea as for the avg aggregator before: Most of the time, there is
no overflow, so we don't have to revert to the more expensive and less
precise incremental calculation of the mean value.
Signed-off-by: beorn7 <beorn@grafana.com>