Fix Sorting by _lastUpdated #904
Description
Sorting resources by _lastUpdated can return a resource more than once.
The problem with the meta.lastUpdated property is that it doesn't contribute to the content hash of a resource because it's not part of the resource content. This results in multiple entries into the SearchParamValueResource index having the same content hash. If that content hash is equal to the current one, the resource is returned multiple times.
This issue is related to #882