`getroute` returns route even after channel has closed

### Issue and Steps to Reproduce
I don't know if it's exactly reproducible as is, but after opening a zero conf channel, making a payment, and then closing it, the channel continues to show up in `get route` well beyond it being closed (even after 100 blocks where it is "forgotten").

### `getinfo` output

Here's the "receiver":

```
❯ ./lightning-cli --network regtest --lightning-dir=/Users/tony/.lightning2 --rpc-file=lightning-rpc2 getinfo
{
"id": "03bacc7cc5292bf928e809b58cf5d61b3b7f60be130953d1f9b901c500fe8e305d",
"alias": "LATENTTRAWL",
"color": "03bacc",
"num_peers": 1,
"num_pending_channels": 0,
"num_active_channels": 0,
"num_inactive_channels": 0,
"address": [
{
"type": "ipv4",
"address": "0.0.0.0",
"port": 18846
}
],
"binding": [
{
"type": "ipv4",
"address": "0.0.0.0",
"port": 18846
}
],
"version": "v0.12.1-1-g475c9bd",
"blockheight": 302,
"network": "regtest",
"fees_collected_msat": 0,
"lightning-dir": "/Users/tony/.lightning2/regtest",
"our_features": {
"init": "08a000080269a2",
"node": "88a000080269a2",
"channel": "",
"invoice": "02000000024100"
}
}
```

here's showing that there is no channels with the payer
```
❯ ./lightning-cli --network regtest --lightning-dir=/Users/tony/.lightning2 --rpc-file=lightning-rpc2 listpeers
{
"peers": [
{
"id": "02a0ae3dfaf741ad5adc9be264cf0003e26998123c4c4de97938d1c32c15d29679",
"connected": true,
"netaddr": [
"127.0.0.1:58233"
],
"features": "08a000080269a2",
"channels": []
}
]
}
```

here's the payer `getroute` call:

```
❯ ./lightning-cli --network regtest getroute id=03bacc7cc5292bf928e809b58cf5d61b3b7f60be130953d1f9b901c500fe8e305d fromid=02a0ae3dfaf741ad5adc9be264cf0003e26998123c4c4de97938d1c32c15d29679 amount_msat=10000000 riskfactor=0 maxhops=1
{
"route": [
{
"id": "03bacc7cc5292bf928e809b58cf5d61b3b7f60be130953d1f9b901c500fe8e305d",
"channel": "13858584x8152606x12487",
"direction": 0,
"amount_msat": 10000000,
"delay": 9,
"style": "tlv"
}
]
}
```

That channel existed previously, and after close (but before the 100 mined blocks after close), this is what it looked like from the payer side:

```
{
"id": "03bacc7cc5292bf928e809b58cf5d61b3b7f60be130953d1f9b901c500fe8e305d",
"connected": true,
"netaddr": [
"127.0.0.1:18846"
],
"features": "08a000080269a2",
"channels": [
{
"state": "ONCHAIN",
"scratch_txid": "a91fc84de58f8c2909f4eb1a606a6df17e44c1be24d90b496084aa4db8177589",
"last_tx_fee_msat": 170000,
"feerate": {
"perkw": 253,
"perkb": 1012
},
"owner": "onchaind",
"short_channel_id": "188x1x1",
"direction": 0,
"channel_id": "01ef7bf166ef4dd182a8ad42cd61a20d420f354f0b484f1fffa0612dc0ecde9c",
"funding_txid": "9ddeecc02d61a0ff1f4f480b4f350f420da261cd42ada882d14def66f17bef01",
"funding_outnum": 1,
"close_to_addr": "bcrt1q7hmctqxfk2t93k3nrcphh749pfacz5sthudsjl",
"close_to": "0014f5f78580c9b29658da331e037bfaa50a7b81520b",
"private": true,
"opener": "local",
"closer": "remote",
"alias": {
"local": "13858584x8152606x12487",
"remote": "722820x14594877x23379"
},
"features": [
"option_static_remotekey"
],
"funding": {
"local_funds_msat": "20000000msat",
"remote_funds_msat": "0msat",
"pushed_msat": 0
},
"to_us_msat": 8000000,
"min_to_us_msat": 8000000,
"max_to_us_msat": 20000000,
"total_msat": 20000000,
"fee_base_msat": 1,
"fee_proportional_millionths": 10,
"dust_limit_msat": 546000,
"max_total_htlc_in_msat": 18446744073709551615,
"their_reserve_msat": 546000,
"our_reserve_msat": 546000,
"spendable_msat": 6914000,
"receivable_msat": 11454000,
"minimum_htlc_in_msat": 0,
"minimum_htlc_out_msat": 0,
"maximum_htlc_out_msat": 19454000,
"their_to_self_delay": 6,
"our_to_self_delay": 6,
"max_accepted_htlcs": 483,
"state_changes": [
{
"timestamp": "2023-01-05T17:12:58.159Z",
"old_state": "CHANNELD_AWAITING_LOCKIN",
"new_state": "CHANNELD_NORMAL",
"cause": "user",
"message": "Lockin complete"
},
{
"timestamp": "2023-01-05T18:19:26.356Z",
"old_state": "CHANNELD_NORMAL",
"new_state": "CHANNELD_SHUTTING_DOWN",
"cause": "remote",
"message": "Peer closes channel"
},
{
"timestamp": "2023-01-05T18:19:26.373Z",
"old_state": "CHANNELD_SHUTTING_DOWN",
"new_state": "CLOSINGD_SIGEXCHANGE",
"cause": "remote",
"message": "Start closingd"
},
{
"timestamp": "2023-01-05T18:19:26.383Z",
"old_state": "CLOSINGD_SIGEXCHANGE",
"new_state": "CLOSINGD_COMPLETE",
"cause": "remote",
"message": "Closing complete"
},
{
"timestamp": "2023-01-05T18:19:42.851Z",
"old_state": "CLOSINGD_COMPLETE",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:19:42.873Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:26:54.843Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:26:54.849Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:27:12.138Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:27:12.145Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:29:46.167Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:29:46.174Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:30:02.637Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:30:02.644Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:30:10.889Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:30:10.895Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:31:22.070Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:31:22.076Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
},
{
"timestamp": "2023-01-05T18:31:33.359Z",
"old_state": "ONCHAIN",
"new_state": "FUNDING_SPEND_SEEN",
"cause": "remote",
"message": "Onchain funding spend"
},
{
"timestamp": "2023-01-05T18:31:33.366Z",
"old_state": "FUNDING_SPEND_SEEN",
"new_state": "ONCHAIN",
"cause": "remote",
"message": "Onchain init reply"
}
],
"status": [
"ONCHAIN:Tracking mutual close transaction",
"ONCHAIN:All outputs resolved: waiting 88 more blocks before forgetting channel"
],
"in_payments_offered": 0,
"in_offered_msat": 0,
"in_payments_fulfilled": 0,
"in_fulfilled_msat": 0,
"out_payments_offered": 3,
"out_offered_msat": 12000000,
"out_payments_fulfilled": 3,
"out_fulfilled_msat": 12000000,
"htlcs": []
},
```

Indicating it was mutually closed. I'll see if I can easily reproduce this, but currently it's pretty nasty for an LSP to think there's a route to the receiver when there's not. Could be related to other bugs around `getroute` : https://github.com/ElementsProject/lightning/issues/5878