captest: Remove `fsm_setopaque` in carryopaque callback.
captest: Remove `fsm_setopaque` in carryopaque callback.

This will also be removed by changes that are about to land on a PR,
but are also removed here because `src_set[i]` is becoming const.

katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm