Description of problem:
On a setup that has been upgraded from 6.11, one can't save any Bootdisk related settings.

Version-Release number of selected component (if applicable):
rubygem-foreman_bootdisk-19.0.6-1.el8sat.noarch
satellite-6.12.0-4.el8sat.noarch


How reproducible:
100%

Steps to Reproduce:
1. install 6.11
2. upgrade to 6.12
3. go to settings → bootdisk
4. try to edit a setting, like Grub2 directory

Actual results:
500 Error

production log reads:
2022-11-02T06:01:22 [I|app|3956271e] Started PUT "/api/settings/bootdisk_grub2_dir" for 10.39.195.157 at 2022-11-02 06:01:22 -0400
2022-11-02T06:01:22 [I|app|3956271e] Processing by Api::V2::SettingsController#update as JSON
2022-11-02T06:01:22 [I|app|3956271e]   Parameters: {"setting"=>{"value"=>"[FILTERED]"}, "apiv"=>"v2", "id"=>"bootdisk_grub2_dir"}
2022-11-02T06:01:22 [W|app|3956271e] Action failed
2022-11-02T06:01:22 [I|app|3956271e] Backtrace for 'Action failed' error (ActiveRecord::SubclassNotFound): Invalid single-table inheritance type: Setting::Bootdisk is not a subclass of Setting
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/inheritance.rb:241:in `find_sti_class'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/inheritance.rb:215:in `discriminate_class_for_record'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/persistence.rb:257:in `instantiate'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/querying.rb:58:in `block (2 levels) in find_by_sql'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/result.rb:62:in `block in each'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/result.rb:62:in `each'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/result.rb:62:in `each'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/querying.rb:58:in `map'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/querying.rb:58:in `block in find_by_sql'
 3956271e | /usr/share/gems/gems/activesupport-6.0.4.7/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/querying.rb:56:in `find_by_sql'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation.rb:824:in `block in exec_queries'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation.rb:842:in `skip_query_cache_if_necessary'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation.rb:811:in `exec_queries'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation.rb:626:in `load'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation.rb:250:in `records'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation/finder_methods.rb:499:in `find_take'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation/finder_methods.rb:98:in `take'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/relation/finder_methods.rb:81:in `find_by'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/querying.rb:21:in `find_by'
 3956271e | /usr/share/gems/gems/activerecord-6.0.4.7/lib/active_record/core.rb:183:in `find_by'
 3956271e | /usr/share/foreman/app/services/setting_registry.rb:181:in `_find_or_new_db_record'
 3956271e | /usr/share/foreman/app/services/setting_registry.rb:82:in `set_user_value'
 3956271e | /usr/share/foreman/app/controllers/api/v2/settings_controller.rb:54:in `update'

Expected results:
No error, setting is saved

Additional info:
This is because the DB was not migrated to use `Setting` instead of `Setting::Bootdisk` as the category of the settings.