Fix what bolt2_open_channel_sending_node_checks_part1 tests

There are currently two issues with
`bolt2_open_channel_sending_node_checks_part1` which counteract
each other and hide that the test isn't testing what it should be.

First of all, the final `create_channel` call actually fails
because we try to open a channel with ourselves, instead of
panicing as the test is supposed to check for.

However, when we fix the create_channel call to panic, when we
drop `nodes[1]` after `create_channel` panics, we fail the
no-pending-messages test as it as an expeted `accept_channel` in
its outbound buffer. This causes a double-panic.

Previously, these two offset each other - instead of panicing in
`create_channel` we'd panic in the Node drop checks.

This fixes both by fetching the `accept_channel` before we go into
the panic'ing `create_channel` call (who's arguments were
		corrected).

Author: TheBlueMatt

lightning/src/ln/functional_tests.rs

@@ -6010,9 +6010,10 @@ fn bolt2_open_channel_sending_node_checks_part1() { //This test needs to be on i
 	nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), channel_value_satoshis, push_msat, 42, None).unwrap();
 	let node0_to_1_send_open_channel = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
 	nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), InitFeatures::known(), &node0_to_1_send_open_channel);
+	get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
 
 	//Create a second channel with a channel_id collision
-	assert!(nodes[0].node.create_channel(nodes[0].node.get_our_node_id(), channel_value_satoshis, push_msat, 42, None).is_err());
+	assert!(nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), channel_value_satoshis, push_msat, 42, None).is_err());
 }
 
 #[test]