There is no way to turn off this as_server logging.
It is hard coded and not driven by variable ISDBGACTIV.
CAUAJM_I_30032 Client [CA WAAE AutoRep:8729][xxxxxx:49695:127.0.1.1] [0xffc54bfc][05/18/2017 02:37:46.9834][0:root@xxxxxxxx> 0] API ID  execution completed. Total time: 0.046 seconds.
CAUAJM_I_30031 Client [CA WAAE AutoRep:8729][xxxxxxx:49695:127.0.1.1] [0xffc54b80][05/18/2017 02:37:47.0459][0:root@xxxxxxx> 0] API ID  execution started.
An enhancement request has already been opened here