Replace all remaining tor_mem_is_zero() with fast_mem_is_zero()

src/core/mainloop/connection.c

src/core/or/channeltls.c

src/core/or/circuitbuild.c

src/feature/client/bridges.c

src/feature/dirauth/dirvote.c

src/feature/dirauth/dsigs_parse.c

src/feature/dirauth/shared_random.c

src/feature/dirauth/shared_random_state.c

src/feature/dirclient/dirclient.c

src/feature/dircommon/voting_schedule.c

src/feature/dirparse/ns_parse.c

src/feature/hs/hs_common.c

src/feature/hs/hs_descriptor.c

src/feature/hs/hs_intropoint.c

src/feature/hs/hs_service.c

src/feature/nodelist/fmt_routerstatus.c

src/feature/nodelist/microdesc.c

src/feature/nodelist/nodelist.c

src/feature/nodelist/routerlist.c

src/feature/nodelist/torcert.c