Remove old benchmarks
c.f.: https://foss.heptapod.net/fluiddyn/fluidsim-bench-results for the right results used in the fluidsim article
All legacy (hg-git based) Projects have been automatically migrated to native with the upgrade of 2025-01-23
c.f.: https://foss.heptapod.net/fluiddyn/fluidsim-bench-results for the right results used in the fluidsim article