My configuration is as follows:
My goal is that all files are written to S3 instead of MySQL, but I'm not entirely sure how to disable the MySQL storage engine.
Set storage.mysql-engine.max-size to 0 (also, this config option is missing a description?). See:
MySQL storage is configured by default, for files up to (just under) 1MB. You can configure it with these keys:
storage.mysql-engine.max-size: Change the filesize limit. Set to 0 to disable.