Benchmarker: remove duplicate navigation buttons that don't change the other one when clicked on

Field feedback.

They are in benchmarkReport.html.ftl, and both times nicely marked with

<!-- HACK Duplication to show the navigation tabs in the same viewport as the tables -->

So why haven't I removed them yet? Because we need to check what happens with big tables how it behaves without these...

We should probably first upgrade to twitter bootstrap 3.