Use namespace runner for codspeed benchmarks

[Alex-PLACET]

Use namespace runner for codespeed benchmarks
About performances, we almost cut by half the build and benchmark times with a machine with the same number of cores and the half of RAM.

[codspeed-hq]

Merging this PR will not alter performance

✅ 255 untouched benchmarks

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_{Comparing Alex-PLACET:use-namespace-runner (25ccb3d) with master (37e4b58)}