Avoid peer penalties on internal errors for batch block import (#2898)

## Issue Addressed

NA

## Proposed Changes

I've observed some Prater nodes (and potentially some mainnet nodes) banning peers due to validator pubkey cache lock timeouts. For the `BeaconChainError`-type of errors, they're caused by internal faults and we can't necessarily tell if the peer is bad or not. I think this is causing us to ban peers unnecessarily when running on under-resourced machines.

## Additional Info

NA

beacon_node/network/src/sync/manager.rs

@@ -137,7 +137,10 @@ pub enum BatchProcessResult {
     /// The batch was completed successfully. It carries whether the sent batch contained blocks.
     Success(bool),
     /// The batch processing failed. It carries whether the processing imported any block.
-    Failed(bool),
+    Failed {
+        imported_blocks: bool,
+        peer_action: Option<PeerAction>,
+    },
 }
 
 /// Maintains a sequential list of parents to lookup and the lookup's current state.