fix: do not add peers to routing table during RPC handling (libp2p#2866)

This can cause a race condition where two peers try to bootstrap to each other, then fail to add the other to the routing table because they wait for the other to respond to a ping first.

It also fixes a smaller bug whereby we'd try to add a peer to the routing table after they send us an RPC message but they are a DHT client - they'd not respond to the ping we send before adding them so it's a waste of resources.

packages/kad-dht/src/rpc/index.ts

@@ -95,12 +95,6 @@ export class RPC {
       const { stream, connection } = data
       const peerId = connection.remotePeer
 
-      try {
-        await this.routingTable.add(peerId)
-      } catch (err: any) {
-        this.log.error(err)
-      }
-
       const self = this // eslint-disable-line @typescript-eslint/no-this-alias
 
       await pipe(

packages/kad-dht/test/rpc/handlers/ping.spec.ts

@@ -2,7 +2,6 @@
 
 import { defaultLogger } from '@libp2p/logger'
 import { expect } from 'aegir/chai'
-import { fromString as uint8ArrayFromString } from 'uint8arrays/from-string'
 import { type Message, MessageType } from '../../../src/message/dht.js'
 import { PingHandler } from '../../../src/rpc/handlers/ping.js'
 import { createPeerId } from '../../utils/create-peer-id.js'
@@ -30,7 +29,6 @@ describe('rpc - handlers - Ping', () => {
   it('replies with the same message', async () => {
     const msg: Message = {
       type: T,
-      key: uint8ArrayFromString('hello'),
       closer: [],
       providers: []
     }