Refactor CatalogCache::_scheduleCollectionRefresh function

The CatalogCache::_scheduleCollectionRefresh logic is implemented using a mix of callbacks and recursion. This makes particularly difficult to follow the execution flow.
Moreover this code is even more difficult to follow because the result forwarded to the callback is handled by an internal function and not from the main callback logic.

Once SERVER-49292 is committed this function should be refactored in order to address the outlined issues.