Hello Korbinian,
at the moment there is no option (even not via the API) to influence the log behavior. For each scheduled job as log is written regarding the planned execution, start and end time (and some further information).
In case you get in trouble with the many log entries and in case you do not need obsolete log entries anymore, you can think about a "tidy XS job" which cleans the old log enties, for example all entries which are older than one month. It would also be possible export that log entries via the job to a file if they are necessary later. The job has to clean the entries in table "_SYS_XS"."JOB_LOG" (with the necessary privileges).
From my point of view I would not go that way as long as it is not really necessary. But it is possible.
Best Regards,
Florian