We get a unilateral close if the blocks come too fast:

```
>       l2.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')

tests/test_splicing.py:96:
...
>                   raise TimeoutError('Unable to find "{}" in logs.'.format(exs))
E                   TimeoutError: Unable to find "[re.compile('CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')]" in logs.
```

Here:

```
lightningd-2 2025-07-08T12:08:30.430Z DEBUG   lightningd: Adding block 114: 542499dfc63bc94c0ba0a3d81bdaff07ab73ba9aebddd4c2ae4b2e0c1e8bd15f
...
lightningd-2 2025-07-08T12:08:30.459Z UNUSUAL 0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-chan#1: Peer permanent failure in CHANNELD_AWAITING_SPLICE: Fulfilled HTLC 1 RCVD_REMOVE_REVOCATION cltv11 4 hit deadline (reason=protocol)
lightningd-2 2025-07-08T12:08:30.469Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-channeld-chan#1: Status closed, but not exited. Killing
lightningd-2 2025-07-08T12:08:30.475Z INFO    0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-chan#1: State changed from CHANNELD_AWAITING_SPLICE to AWAITING_UNILATERAL
```

Signed-off-by: Rusty Russell <[email protected]>

```
>       l1.rpc.fundchannel(l2.info['id'], CHANNEL_SIZE)

tests/test_connection.py:667:
...
>           raise RpcError(method, payload, resp['error'])
E           pyln.client.lightning.RpcError: RPC call failed: method: fundchannel, payload: {'id': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59', 'amount': 50000, 'announce': True}, error: {'code': -1, 'message': 'Disconnected', 'data': {'id': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59', 'method': 'openchannel_update'}}
```

What happens here is complicated.

1. dualopend never processes the WIRE_COMMITMENT_SIGNED message, meaning it doesn't consider it worth
   trying to reconnect.
2. Normally, on disconnect, we give subds time to process packets and then notice the disconnect.
3. But, if we can another connection, we terminate the (old) subds immediately.
4. When lightningd transitions the channel from DUALOPEND_OPEN_INIT to DUALOPEND_OPEN_COMMIT_READY,
   it tells connectd this peer is important.
5. Normally, this causes a reconnect one second after hangup.
6. However, if we've already disconnected, it makes connectd reconnect immediately.  This causes
   the test flake, if dualopend hasn't processed the message, and thus changed the state to
   DUALOPEND_OPEN_COMMITTED: we don't reconnect and instead fail the fundchannel() call.

Signed-off-by: Rusty Russell <[email protected]>

l3 closes with l2 unilaterally, but l2 sends l1 the channel_announce after
that, when it has never seen it before.  The solution is to wait until
l1 has seen the channel before we start the rest of the test:

```
E           ValueError:
E           Node errors:
E            - lightningd-2: had warning messages
E            - lightningd-1: had bad gossip messages
...
lightningd-2 2025-07-09T07:55:59.778Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: peer_in WIRE_WARNING
lightningd-2 2025-07-09T07:55:59.778Z INFO    0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Received WIRE_WARNING: WARNING: channel_announcement: no unspent txout 103x1x0
lightningd-1 2025-07-09T07:55:59.781Z DEBUG   022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59-channeld-chan#1: billboard: Channel ready for use.
lightningd-1 2025-07-09T07:55:59.782Z TRACE   gossipd: channel_announcement: got reply for 103x1x0...
lightningd-1 2025-07-09T07:55:59.782Z TRACE   022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59-gossipd: Bad gossip order: channel_announcement: no unspent txout 103x1x0
```

Signed-off-by: Rusty Russell <[email protected]>

Sometimes the feerate is 5 too high.  But without seeing the actual txs it's
looking at, it's hard to know why.

```
actual_feerate = 13005.66942869603, expected_feerate = 13000

    def check_feerate(nodes, actual_feerate, expected_feerate):
        # Feerate can't be lower.
        assert actual_feerate > expected_feerate - 2
        if actual_feerate >= expected_feerate + 2:
            if any([did_short_sig(n) for n in nodes]):
                return
        # Use assert as it shows the actual values on failure
>       assert actual_feerate < expected_feerate + 2
E       AssertionError
```

Signed-off-by: Rusty Russell <[email protected]>