The channel vanishes from listchannels when it's dying, *but* only when it gets deleted
do we consider moving the actual node_announcement. We have to wait until gossipd
has seen the 12 blocks, and move it if necessary.
```
E Full diff:
E {
E 'nodes': [
E - {
E - 'addresses': [],
E - 'alias': 'SILENTARTIST-e986cd2-modded',
E - 'color': '022d22',
E - 'features': '808898880a8a59a1',
E - 'last_timestamp': 1767572731,
E - 'nodeid': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59',
E - },
E {
E 'addresses': [],
E 'alias': 'HOPPINGFIRE-e986cd2-modded',
E 'color': '035d2b',
E 'features': '808898880a8a59a1',
E 'last_timestamp': 1767572731,
E 'nodeid': '035d2b1192dfba134e10e540875d366ebc8bc353d5aa766b80c090b39c3a5d885d',
E },
E {
E 'addresses': [],
E 'alias': 'JUNIORFELONY-e986cd2-modded',
E 'color': '0382ce',
E 'features': '808898880a8a59a1',
E 'last_timestamp': 1767572731,
E 'nodeid': '0382ce59ebf18be7d84677c2e35f23294b9992ceca95491fcf8a56c6cb2d9de199',
E },
E {
E 'addresses': [],
E + 'alias': 'SILENTARTIST-e986cd2-modded',
E + 'color': '022d22',
E + 'features': '808898880a8a59a1',
E + 'last_timestamp': 1767572731,
E + 'nodeid': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59',
E + },
E + {
E + 'addresses': [],
E 'alias': 'JUNIORBEAM-e986cd2-modded',
E 'color': '0266e4',
E 'features': '808898880a8a59a1',
E 'last_timestamp': 1767572732,
E 'nodeid': '0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518',
E },
E ],
E }
tests/test_gossip.py:2390: AssertionError
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
082e70aada