grltrackerplaylists: Improve performance of "Recently Played" query

As the query goes, we query all songs played after a fixed date, merge it tracker-miner-fs-3 data, then pick the 50 most recent ones. Take the filter on the lastPlayed date outside of the larger query, so it only applies to the 50 most recent songs returned.

This happened to be the main bottleneck on the query, since nie:contentAccessed is not an indexed property, and this check would run for all songs that were ever played, before ordering the results and limiting to 50 elements.