PromLab - Limited accuracy on rate-increase-delta-predict_linear

[aurrelhebert]

Based on PromLab PromQL compliance tests (https://promlabs.com/promql-compliance-tests), we don't reproduce the exact computation for the function rate-increase-delta-predict_linear which leads to less accuracy on queries results with a low range (example for delta function):
QUERY: delta(demo_cpu_usage_seconds_total[15s])

-  Value: Inverse(TranslateFloat64, float64(30.170983173889805)),
+  Value: Inverse(TranslateFloat64, float64(29.886138000001665)),
...

`
QUERY: delta(demo_cpu_usage_seconds_total[1m])

QUERY: delta(demo_cpu_usage_seconds_total[5m])
`