pytest: test to crash on migration from old db.

```
Error executing statement: wallet/wallet.c:3247: INSERT INTO channel_htlcs ( id, channel_id, channel_htlc_id, direction, origin_htlc, msatoshi, cltv_expiry, payment_hash, payment_key, hstate, routing_onion, malformed_onion, partid, groupid, fees_msat, min_commit_num) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 0, ?, ?, ?, ?);: UNIQUE constraint failed: channel_htlcs.id
lightningd: FATAL SIGNAL 6 (version v25.02-321-g3999879)
0x642e42dc974f send_backtrace
	common/daemon.c:33
0x642e42dc97eb crashdump
	common/daemon.c:78
0x7d90f2e4532f ???
	./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0
0x7d90f2e9eb2c __pthread_kill_implementation
	./nptl/pthread_kill.c:44
0x7d90f2e9eb2c __pthread_kill_internal
	./nptl/pthread_kill.c:78
0x7d90f2e9eb2c __GI___pthread_kill
	./nptl/pthread_kill.c:89
0x7d90f2e4527d __GI_raise
	../sysdeps/posix/raise.c:26
0x7d90f2e288fe __GI_abort
	./stdlib/abort.c:79
0x642e42d71f79 fatal_vfmt
	lightningd/log.c:1055
0x642e42da61e8 db_error
	wallet/db.c:1117
0x642e42e1eafc db_fatal
	db/utils.c:323
0x642e42e1eee6 db_exec_prepared_v2
	db/utils.c:197
0x642e42db1fd9 wallet_htlc_save_out
	wallet/wallet.c:3310
0x642e42d8f07f update_out_htlc
	lightningd/peer_htlcs.c:1978
0x642e42d8f435 changed_htlc
	lightningd/peer_htlcs.c:2011
0x642e42d929aa peer_sending_commitsig
	lightningd/peer_htlcs.c:2108
0x642e42d5002f channel_msg
	lightningd/channel_control.c:1533
0x642e42d9ec3a sd_msg_read
	lightningd/subd.c:560
0x642e42e88435 next_plan
	ccan/ccan/io/io.c:60
0x642e42e88906 do_plan
	ccan/ccan/io/io.c:422
0x642e42e889c3 io_ready
	ccan/ccan/io/io.c:439
0x642e42e8a332 io_loop
	ccan/ccan/io/poll.c:455
0x642e42d69b01 io_loop_with_timers
	lightningd/io_loop_with_timers.c:22
0x642e42d6f525 main
	lightningd/lightningd.c:1486
0x7d90f2e2a1c9 __libc_start_call_main
	../sysdeps/nptl/libc_start_call_main.h:58
0x7d90f2e2a28a __libc_start_main_impl
	../csu/libc-start.c:360
0x642e42d41b64 ???
	???:0
0xffffffffffffffff ???
```

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

Author: rustyrussell