breaks prunes data into chunks to fit into packets (#13613)

Validator logs show that prune messages are dropped because they exceed
packet data size:
https://github.com/solana-labs/solana/blob/f25c969ad/perf/src/packet.rs#L90-L92
This can exacerbate gossip traffic by redundantly increasing push
messages across network. The workaround is to break prunes into smaller
chunks and send over in multiple messages.

perf/src/packet.rs

@@ -88,6 +88,9 @@ pub fn to_packets_with_destination<T: Serialize>(
     for (dest_and_data, o) in dests_and_data.iter().zip(out.packets.iter_mut()) {
         if !dest_and_data.0.ip().is_unspecified() && dest_and_data.0.port() != 0 {
             if let Err(e) = Packet::populate_packet(o, Some(&dest_and_data.0), &dest_and_data.1) {
+                // TODO: This should never happen. Instead the caller should
+                // break the payload into smaller messages, and here any errors
+                // should be propagated.
                 error!("Couldn't write to packet {:?}. Data skipped.", e);
             }
         } else {