open-api: disable javadoc parsing by default

Please disable the Javadoc parser by default, or at least provide a switch to control it.

After migrating from Jooby 3 to 4, all Javadoc comments are suddenly exposed in Swagger, even though they were not intended to be public before. These comments may contain internal information, developer notes, or markers such as `TODO`, `FIXME`, or, even worse.