Clarifying which fields are internal in the database configuration

Some fields in the database configuration are set with an equal sign (e.g `usable_regions=1`), and some are set with a colon-and-equal-sign (e.g. `log_version:=3`). These both appear in the same object in the database configuration in the JSON status, so it may not not clear to administrators what the difference between the two kinds of fields are. I have heard that the second style of field are meant to be for internal use only. If that is true, we should signal them more clearly in the configuration, such as by moving them to a discrete section for internal flags.

No files, tests, or entry points are named. Start by confirming whether colon-equals fields are internal-only and identify where the database configuration is rendered in JSON status; done means administrators can clearly distinguish internal fields from regular fields in that configuration.

Written by the indexing model from the issue text.