Consolidate use of IndexSettingProviders #137581
Description
There are many places that pull in settings from IndexSettingProviders in various ways (and some that don't that probably ought to). Recent uses include #136214 and #137407. The code is repeated in a few places. We need to survey everywhere that is using IndexSettingProviders and ought to be using IndexSettingProviders, and have it all use a common method for adding additional settings.