Speed up mediaitems_view

[KillerX]

mediaitems_view is is a frequently used view.
It appears to have slowed down significantly with more data.

After some preliminary investigation it appears that by removing the timed metadata subquery the execution can be sped up by ~50-60% (~1.2 sec -> 0.4 sec). Further improvements may be possible.

This would mean offloading the subquery an only running it when needed, i.e. not when we need shorts. This has a direct impact on shorts loading time for cases where the results are not in cache.

Increase cache time