Prior to 23.05, we used this tag to mark onchain to-self inputs we didn't
wait for (because they were too small). This fixes migration if that happened
(and we are debating whether we should re-introduce this!).
```
lightningd: FATAL SIGNAL 6 (version v25.09rc2)
0x100c8683 send_backtrace
common/daemon.c:33
0x100c876f crashdump
common/daemon.c:78
0x7fffb2080493 ???
???:0
0x7fffb1ab0cac ???
__pthread_kill_implementation+0x1bc:0
0x7fffb1a48a5b ???
__GI_raise+0x2b:0
0x7fffb1a2a3db ???
__GI_abort+0x153:0
0x100935b7 migrate_from_account_db
wallet/account_migration.c:424
0x10093ff7 db_migrate
wallet/db.c:1139
0x10096763 db_setup
wallet/db.c:1185
0x100a1bcb wallet_new
wallet/wallet.c:223
0x1004485f main
lightningd/lightningd.c:1311
0x7fffb1a2aba3 ???
__libc_start_call_main+0x93:0
0x7fffb1a2adeb ???
__libc_start_main_alias_1+0x1ab:0
0xffffffffffffffff ???
???:0
lightningd: Died with signal 6
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: https://github.com/ElementsProject/lightning/issues/8484
22a5e9e7e6