We need to efficiently rebuild caches when rebuilding the defaults of exportable entities.
When Rules saves a new configuration, it has to clear its caches in order to update the actions/conditions that are available for a component and/or to update caches for efficient execution of reaction rules or components.
However, any operations running on Rules configuration insert/update that require the rules cache would so trigger rules cache building, whereas the next update would flush the cache again - leading to repeated cache builds and bad performance.
Thus, we need to add a hook that allows modules to efficiently act on configuration mass-updates as occurring when rebuilding defaults in code. The Rules use-case is for rules-i18n at, which needs to scan for translatable action parameters that have changed and requires the rules-cache to do so.