Description of problem:
From a user perspective, it is tricky-to-impossible to reset a Settings value once modified from its default (if there is a default). User does not know what the default is ("is empty string the same like nil value..?"), some defaults are "hidden" just in source code.

An experienced user can follow (unsupported, not reocmmended in general) procedure "delete the settings row from foreman DB, restart dynflow+foreman services", but that is something we should not recommend to customers.

Please provide an API and/or hammer option to reset a Settings.

Version-Release number of selected component (if applicable):
6.13

How reproducible:
100%

Steps to Reproduce:
1. Change "Entries per page" or "CDN SSL version" settings.
2. Try to unset / reset to defaults.

Actual results:
2. "Entries per page" has some default value unknown to user and there is no way to reset the cusomization (providing there empty string, I get "malformed format string" error). "CDN SSL version" does not even have a default option.

Expected results:
2. e.g. a "hammer settings reset" subcommand available (or some other means for the same).

Additional info: