[!310] Change scaling of autotune results

Merge branch 'experiments/autotune' into 'master'

ref:extensions/dune-codegen The scaling of the autotune results was bugged.

See merge request [extensions/dune-codegen!310]

  [extensions/dune-codegen!310]: gitlab.dune-project.org/extensions/dune-codegen/merge_requests/310