lightningd: don't ignore fee limits on mutual close.

LDK will pick the *upper* limit (see: lightningdevkit/rust-lightning#3014)!

It should not do this, but since you can set a manual range for mutual close, it's probably better to disable this option for close, as it's even more dangerous than documented.

Changelog-Changed: config/JSON: --ignore-fee-limits / setchannel ignorefeelimits no longer applies to mutual close.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: ElementsProject#7242

lightningd/closing_control.c

@@ -427,9 +427,6 @@ void peer_start_closingd(struct channel *channel, struct peer_fd *peer_fd)
 	if (channel->closing_feerate_range) {
 		min_feerate = channel->closing_feerate_range[0];
 		max_feerate = channel->closing_feerate_range[1];
-	} else if (channel->ignore_fee_limits || ld->config.ignore_fee_limits) {
-		min_feerate = 253;
-		max_feerate = 0xFFFFFFFF;
 	}
 
 	/* BOLT #3:

tests/test_closing.py

@@ -4044,7 +4044,6 @@ def test_closing_no_anysegwit_retry(node_factory, bitcoind):
     l1.rpc.close(l2.info['id'], destination=oldaddr)
 
 
-@pytest.mark.xfail(strict=True)
 def test_closing_ignore_fee_limits(node_factory, bitcoind, executor):
     """Don't use ignore-fee-limits on mutual close: LDK takes us to the cleaners if we do!"""
     l1, l2 = node_factory.line_graph(2, opts=[{'may_reconnect': True,