test: replace (send_message + sync_with_ping) with send_and_ping

test/functional/rpc_blockchain.py

@@ -315,8 +315,7 @@ class BlockchainTest(BitcoinTestFramework):
         def solve_and_send_block(prevhash, height, time):
             b = create_block(prevhash, create_coinbase(height), time)
             b.solve()
-            node.p2p.send_message(msg_block(b))
-            node.p2p.sync_with_ping()
+            node.p2p.send_and_ping(msg_block(b))
             return b
 
         b21f = solve_and_send_block(int(b20hash, 16), 21, b20['time'] + 1)