retiring the old legacypay command in CLN v0.11.0

Tests:

Bring up to LN nodes:

On LN#2, create an invoice:

lnurl/tests % docker exec -it `docker ps -q -f "name=lightning2\."` lightning-cli --lightning-dir=/.lightning invoice 10000 "label6666" "t1d" 300
{
  "payment_hash": "65b725ca04b6fe16ab7e0d6736e1ac14be2755ad1c3545cbb6502fe8979ff866",
  "expires_at": 1658190000,
  "bolt11": "lnbcrt100n1p3dtauysp5zhdqs9l65035qflwj22890zu5s6ckz82s8d8muusqw79axhzynlspp5vkmjtjsykmlpd2m7p4nndcdvzjlzw4ddrs65tjak2qh739ullpnqdq9wsckgxqzfvcqp29qyysgq6ywhd3s3dgedh7s4wfl4syx8t5rg3flsg60gcvpktrywfj4lmz3rfw93lh9vlg2hdwlukecv34h39s3x709tqny7fmg5g0hafndqnnspezudwa",
  "payment_secret": "15da0817faa3e34027ee929472bc5ca4358b08ea81da7df39003bc5e9ae224ff",
  "warning_deadends": "Insufficient incoming capacity, once dead-end peers were excluded"
}

With CN-LN #1, pay the invoice (ln_pay):

Testing ln_pay... bolt11=lnbcrt100n1p3dtauysp5zhdqs9l65035qflwj22890zu5s6ckz82s8d8muusqw79axhzynlspp5vkmjtjsykmlpd2m7p4nndcdvzjlzw4ddrs65tjak2qh739ullpnqdq9wsckgxqzfvcqp29qyysgq6ywhd3s3dgedh7s4wfl4syx8t5rg3flsg60gcvpktrywfj4lmz3rfw93lh9vlg2hdwlukecv34h39s3x709tqny7fmg5g0hafndqnnspezudwa

 % Total  % Received % Xferd Average Speed  Time  Time   Time Current
                 Dload Upload  Total  Spent  Left Speed
 0   0  0   0  0   0   0   0 --:--:-- --:--:-- --:--:--   0*  Trying 10.0.1.28:8888...
* Connected to proxy (10.0.1.28) port 8888 (#0)
> POST /ln_pay HTTP/1.1
> Host: proxy:8888
> User-Agent: curl/7.83.1
> Accept: */*
> Content-Type: application/json
> Content-Length: 330
> 
} [330 bytes data]
100  330  0   0 100  330   0  149 0:00:02 0:00:02 --:--:--  149* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Content-Type: application/json
< Content-Length: 406
< 
{ [406 bytes data]
100  736 100  406 100  330  143  116 0:00:02 0:00:02 --:--:--  259
* Connection #0 to host proxy left intact
response={"destination":"026daa77dfae51bf14b1e4e09bee7392850d373ce127ae10fea9a2a44aa9fdb443","payment_hash":"65b725ca04b6fe16ab7e0d6736e1ac14be2755ad1c3545cbb6502fe8979ff866","created_at":1658189764.481,"parts":1,"msatoshi":10000,"amount_msat":"10000msat","msatoshi_sent":10000,"amount_sent_msat":"10000msat","payment_preimage":"4d6a16fa8f9afe1ccf2f97b5835e86ea1affe8b465be6bf7b58055fa5505fd9e","status":"complete"}
Tested ln_pay.

SatoshiPortal / cyphernode

retiring the old legacypay command in CLN v0.11.0 #276