Optimize do_remove_all_certs_received_by

• Optimize do_remove_all_certs_received_by by factoring stuff from do_remove_cert
• Fix off-by-one in benchmarking of the call remove_all_certs_received_by (benchmarking was against 1 certification less than the call)

This will reduce the weight of the root call remove_all_certs_received_by and of revocation. Emitted events are the same. A little optimization is still possible, as on_removed is still called N times and checks membership each time (only the last call will revoke membership), but it would require API changes, and the overhead is not that big.

Weights were updated with dummy values, not from benchmarking, so they don't reflect the optimization yet.

Fixes #254 (closed)