Make logscale in reqerror graphs actually work

Also tweak graph titles.
This fix depends on a graphite update which AFAIK already happened.
10 as log base: the yearly graph has values across 4 orders of magnitudes.

Bug: 41754
Change-Id: Iae1c2b97f3f81e60c27a8af5cbd33f772576bbe3
Merge "Make logscale in reqerror graphs actually work" into production