runes: bug fix for db failure to upgrade due to runes table alteration #6770

While rebasing the PR for per rune restriction, I unintentionally merged the
`{SQL("ALTER TABLE runes ADD last_used_nsec BIGINT DEFAULT NULL"), NULL}` database
alteration command ahead of {NULL, migrate_runes_idfix} (commit eacf0b502c (diff-1abcdf1b9d822b30079d6450b790274bdfb7c7fa04baa43ad2d9bd449865d4c9R978)).

`migrate_runes_idfix` was the 234th change (deployed with version 23.08.1)
and adding the `last_used_nsec` column should have been the next
(235th, added in current release) change. Due to this incorrect ordering,
nodes updating from version 23.08.1 to the master branch will not add the
`last_used_nsec` column as they should, and instead execute `migrate_runes_idfix`
again, leading to the error in issue #6770.

After the reordering, db_get_runes method also has to be fixed for only
selecting rune NOT last_used_nsec. Because this column was added after
`migrate_runes_idfix` calls it. I am tempted to change the method name from
`db_get_runes` to `db_migrate_runes` for more clarity on its functionality though.

Changelog-None.

wallet/db.c

@@ -975,8 +975,8 @@ static struct migration dbmigrations[] = {
     {SQL("ALTER TABLE htlc_sigs ADD inflight_tx_outnum INTEGER"), NULL},
     {SQL("ALTER TABLE channel_funding_inflights ADD splice_amnt BIGINT DEFAULT 0"), NULL},
     {SQL("ALTER TABLE channel_funding_inflights ADD i_am_initiator INTEGER DEFAULT 0"), NULL},
-    {SQL("ALTER TABLE runes ADD last_used_nsec BIGINT DEFAULT NULL"), NULL},
     {NULL, migrate_runes_idfix},
+    {SQL("ALTER TABLE runes ADD last_used_nsec BIGINT DEFAULT NULL"), NULL},
     {SQL("DELETE FROM vars WHERE name = 'runes_uniqueid'"), NULL},
 };