Single lookup improvements (#5488)

* Fix unexpected `UnrequestedBlobId` and `ExtraBlocksReturned` errors due to race conditions.

* Continue chain segment processing and skip any blocks that are already known, rather than returning an error.

* more de-dup checking

* ensure we don't reset `requested_ids` during rpc download

* better fix

* Merge branch 'unstable' of https://github.com/sigp/lighthouse into more-dup-lookup-fixes

* remove chain hash check

* Merge branch 'fix-block-lookup-race' of https://github.com/jimmygchen/lighthouse into sean-test-lookups

* remove block check

* add back tests

* Log and CI fixes

* undue extra check

* Merge branch 'sean-test-lookups' of https://github.com/realbigsean/lighthouse into sean-test-lookups

* log improvements

* Improve logging

beacon_node/beacon_chain/src/data_availability_checker.rs

@@ -110,8 +110,6 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
         self.processing_cache.read().get(&block_root).cloned()
     }
 
-    /// A `None` indicates blobs are not required.
-    ///
     /// If there's no block, all possible ids will be returned that don't exist in the given blobs.
     /// If there no blobs, all possible ids will be returned.
     pub fn get_missing_blob_ids<V: AvailabilityView<T::EthSpec>>(