Drop lookups for blocks imported via range sync

[dapplion]

Description

In recent testing of v5.2.0 we have observed cases where a lookup get stuck, range sync kicks in and catch up to the head.

However, sync lookup has no knowledge of the result of range sync and the lookup for an already imported block persists. We can make sync lookup aware of blocks imported via range sync and drop them.

This can help recover some situations faster, but it competes with

• Drop stuck lookups #5824

The PR above guarantees that every lookup that is stuck issues a very informative log and is tracked on metrics. If range sync can complete lookups we won't know with so much certainty if the lookup was stuck or not.