Small cleanup that can happen, might also reduce load time for cache loads.

Right now if we load feed data from fresh or cache, we then filter blocked stories from those results.

If we instead, updated feed cache as stories got blocked, we wouldn't need to do it again from cached loads as it would already be up to date. We would only need to filter blocked for feeds if it was fresh.

This doesn't apply to spocs, that has a slightly more complex handling because it's got placements, frequency capping, and flight id migration, so the code paths are separate and different currently. See bug 1606276