[cassandra] Profile the replayer cpu consumption

On a suggestion of @vlorentz, we should profile the cpu consumption of the replayer to check if some kind of optimization can be done to improve the replaying speed which it's limited by our available cpu resources

10:31 est-ce que tu pourrais lancer un replayer avec profiling (python3 -m cProfile -o /tmp/blablabla.pyprof $(which swh) ...) pendant environ un quart d'heure, le killer (avec sigterm, pas sigkill), et m'envoyer le .pyprof ?

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Migrated from T4510 (view on Phabricator)