les: separate peer into clientPeer and serverPeer (#19991)

* les: separate peer into clientPeer and serverPeer

* les: address comments

les/request_test.go

@@ -81,8 +81,7 @@ func testAccess(t *testing.T, protocol int, fn accessTestFn) {
 	// Assemble the test environment
 	server, client, tearDown := newClientServerEnv(t, 4, protocol, nil, nil, 0, false, true)
 	defer tearDown()
-
-	client.handler.synchronise(client.peer.peer)
+	client.handler.synchronise(client.peer.speer)
 
 	// Ensure the client has synced all necessary data.
 	clientHead := client.handler.backend.blockchain.CurrentHeader()