only benchmark once
Summary:
benchmarking N times slows down the test considerably for what feels like
zero testing advantage. getting just some rough benchmark data should
be entirely sufficient for a unit test. when more detailed
benchmarking is required one can easily switch the benchmark macro
Test Plan: 6 times faster test pass
Reviewers: Plasma, apol
Reviewed By: apol
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D22402