Tweak head syncing (#1845)

## Issue Addressed

Fixes head syncing

## Proposed Changes

- Get back to statusing peers after removing chain segments and making the peer manager deal with status according to the Sync status, preventing an old known deadlock
- Also a bug where a chain would get removed if the optimistic batch succeeds being empty

## Additional Info

Tested on Medalla and looking good

beacon_node/network/src/sync/manager.rs

@@ -691,10 +691,7 @@ impl<T: BeaconChainTypes> SyncManager<T> {
                     {
                         SyncState::Synced
                     } else if peers.advanced_peers().next().is_some() {
-                        SyncState::SyncingHead {
-                            start_slot: head,
-                            target_slot: current_slot,
-                        }
+                        SyncState::SyncTransition
                     } else if peers.synced_peers().next().is_none() {
                         SyncState::Stalled
                     } else {