net_processing: drop MaybePunishNodeForTx

Do not discourage nodes even when they send us consensus invalid
transactions.

Because we do not discourage nodes for transactions we consider
non-standard, we don't get any DoS protection from this check in
adversarial scenarios, so remove the check entirely both to simplify the
code and reduce the risk of splitting the network due to changes in tx
relay policy.

test/functional/p2p_invalid_tx.py

@@ -73,7 +73,7 @@ class InvalidTxRequestTest(BitcoinTestFramework):
             tx = template.get_tx()
             node.p2ps[0].send_txs_and_test(
                 [tx], node, success=False,
-                expect_disconnect=template.expect_disconnect,
+                expect_disconnect=False,
                 reject_reason=template.reject_reason,
             )
 
@@ -140,7 +140,6 @@ class InvalidTxRequestTest(BitcoinTestFramework):
         # tx_orphan_2_no_fee, because it has too low fee (p2ps[0] is not disconnected for relaying that tx)
         # tx_orphan_2_invalid, because it has negative fee (p2ps[1] is disconnected for relaying that tx)
 
-        self.wait_until(lambda: 1 == len(node.getpeerinfo()), timeout=12)  # p2ps[1] is no longer connected
         assert_equal(expected_mempool, set(node.getrawmempool()))
 
         self.log.info('Test orphanage can store more than 100 transactions')