build: remove BIP70 configure option
build: remove BIP70 configure option

This was left in after #17165, so that anyone who had been compiling
with (already disabled by default) BIP70 would realise that support
had been completely removed in 0.20.0. However we should be able to
remove it for 0.21.0.

MeshCollider/bitcoin,alecalve/bitcoin,jambolo/bitcoin,anditto/bitcoin,GroestlCoin/GroestlCoin,dscotese/bitcoin,JeremyRubin/bitcoin,andreaskern/bitcoin,Sjors/bitcoin,jamesob/bitcoin,kallewoof/bitcoin,pataquets/namecoin-core,midnightmagic/bitcoin,bitcoinsSG/bitcoin,Xekyo/bitcoin,yenliangl/bitcoin,rnicoll/dogecoin,qtumproject/qtum,andreaskern/bitcoin,particl/particl-core,pataquets/namecoin-core,mm-s/bitcoin,tecnovert/particl-core,ajtowns/bitcoin,MarcoFalke/bitcoin,AkioNak/bitcoin,mm-s/bitcoin,particl/particl-core,jambolo/bitcoin,prusnak/bitcoin,domob1812/namecore,pstratem/bitcoin,Sjors/bitcoin,namecoin/namecore,bitcoinsSG/bitcoin,qtumproject/qtum,sipsorcery/bitcoin,JeremyRubin/bitcoin,alecalve/bitcoin,lateminer/bitcoin,bitcoinknots/bitcoin,jlopp/statoshi,jambolo/bitcoin,anditto/bitcoin,rnicoll/dogecoin,jamesob/bitcoin,pataquets/namecoin-core,dscotese/bitcoin,lateminer/bitcoin,jamesob/bitcoin,bitcoin/bitcoin,practicalswift/bitcoin,Sjors/bitcoin,Xekyo/bitcoin,EthanHeilman/bitcoin,mm-s/bitcoin,tecnovert/particl-core,jonasschnelli/bitcoin,yenliangl/bitcoin,particl/particl-core,bitcoinknots/bitcoin,Xekyo/bitcoin,bitcoinsSG/bitcoin,apoelstra/bitcoin,lateminer/bitcoin,prusnak/bitcoin,fanquake/bitcoin,AkioNak/bitcoin,kallewoof/bitcoin,fanquake/bitcoin,mruddy/bitcoin,midnightmagic/bitcoin,bitcoinknots/bitcoin,instagibbs/bitcoin,practicalswift/bitcoin,rnicoll/dogecoin,domob1812/namecore,GroestlCoin/bitcoin,prusnak/bitcoin,domob1812/bitcoin,GroestlCoin/GroestlCoin,ajtowns/bitcoin,ElementsProject/elements,yenliangl/bitcoin,EthanHeilman/bitcoin,jambolo/bitcoin,jonasschnelli/bitcoin,dscotese/bitcoin,alecalve/bitcoin,practicalswift/bitcoin,GroestlCoin/bitcoin,anditto/bitcoin,ElementsProject/elements,bitcoin/bitcoin,tecnovert/particl-core,kallewoof/bitcoin,bitcoin/bitcoin,jonasschnelli/bitcoin,alecalve/bitcoin,yenliangl/bitcoin,fujicoin/fujicoin,JeremyRubin/bitcoin,midnightmagic/bitcoin,bitcoinknots/bitcoin,prusnak/bitcoin,dscotese/bitcoin,pataquets/namecoin-core,JeremyRubin/bitcoin,ElementsProject/elements,apoelstra/bitcoin,pstratem/bitcoin,namecoin/namecoin-core,namecoin/namecore,sipsorcery/bitcoin,domob1812/bitcoin,rnicoll/dogecoin,namecoin/namecore,namecoin/namecoin-core,anditto/bitcoin,pstratem/bitcoin,litecoin-project/litecoin,practicalswift/bitcoin,namecoin/namecoin-core,jlopp/statoshi,particl/particl-core,bitcoin/bitcoin,lateminer/bitcoin,GroestlCoin/GroestlCoin,pstratem/bitcoin,GroestlCoin/GroestlCoin,mruddy/bitcoin,n1bor/bitcoin,pataquets/namecoin-core,ajtowns/bitcoin,sstone/bitcoin,litecoin-project/litecoin,mm-s/bitcoin,cdecker/bitcoin,domob1812/namecore,practicalswift/bitcoin,fanquake/bitcoin,lateminer/bitcoin,jamesob/bitcoin,sipsorcery/bitcoin,namecoin/namecoin-core,achow101/bitcoin,cdecker/bitcoin,mruddy/bitcoin,MeshCollider/bitcoin,fujicoin/fujicoin,Xekyo/bitcoin,apoelstra/bitcoin,bitcoinsSG/bitcoin,sipsorcery/bitcoin,n1bor/bitcoin,namecoin/namecore,domob1812/bitcoin,MarcoFalke/bitcoin,domob1812/bitcoin,particl/particl-core,tecnovert/particl-core,lateminer/bitcoin,practicalswift/bitcoin,jambolo/bitcoin,fanquake/bitcoin,rnicoll/bitcoin,apoelstra/bitcoin,GroestlCoin/bitcoin,rnicoll/bitcoin,jlopp/statoshi,AkioNak/bitcoin,GroestlCoin/bitcoin,domob1812/namecore,ElementsProject/elements,cdecker/bitcoin,andreaskern/bitcoin,mruddy/bitcoin,anditto/bitcoin,litecoin-project/litecoin,litecoin-project/litecoin,pstratem/bitcoin,jonasschnelli/bitcoin,jonasschnelli/bitcoin,namecoin/namecore,AkioNak/bitcoin,jlopp/statoshi,rnicoll/bitcoin,n1bor/bitcoin,EthanHeilman/bitcoin,AkioNak/bitcoin,namecoin/namecore,litecoin-project/litecoin,andreaskern/bitcoin,sstone/bitcoin,ajtowns/bitcoin,cdecker/bitcoin,pataquets/namecoin-core,fanquake/bitcoin,EthanHeilman/bitcoin,GroestlCoin/bitcoin,Xekyo/bitcoin,MarcoFalke/bitcoin,domob1812/bitcoin,qtumproject/qtum,Sjors/bitcoin,achow101/bitcoin,mm-s/bitcoin,bitcoinknots/bitcoin,midnightmagic/bitcoin,qtumproject/qtum,fanquake/bitcoin,jamesob/bitcoin,domob1812/bitcoin,kallewoof/bitcoin,andreaskern/bitcoin,rnicoll/bitcoin,apoelstra/bitcoin,dscotese/bitcoin,namecoin/namecoin-core,achow101/bitcoin,yenliangl/bitcoin,GroestlCoin/bitcoin,cdecker/bitcoin,sipsorcery/bitcoin,MarcoFalke/bitcoin,domob1812/namecore,instagibbs/bitcoin,MeshCollider/bitcoin,fujicoin/fujicoin,ElementsProject/elements,fujicoin/fujicoin,n1bor/bitcoin,jnewbery/bitcoin,achow101/bitcoin,n1bor/bitcoin,sstone/bitcoin,alecalve/bitcoin,EthanHeilman/bitcoin,fujicoin/fujicoin,kallewoof/bitcoin,qtumproject/qtum,sstone/bitcoin,Sjors/bitcoin,achow101/bitcoin,MeshCollider/bitcoin,jamesob/bitcoin,AkioNak/bitcoin,kallewoof/bitcoin,tecnovert/particl-core,cdecker/bitcoin,bitcoin/bitcoin,jlopp/statoshi,ajtowns/bitcoin,MeshCollider/bitcoin,litecoin-project/litecoin,GroestlCoin/GroestlCoin,MeshCollider/bitcoin,n1bor/bitcoin,rnicoll/bitcoin,achow101/bitcoin,pstratem/bitcoin,JeremyRubin/bitcoin,bitcoin/bitcoin,jlopp/statoshi,jnewbery/bitcoin,JeremyRubin/bitcoin,mm-s/bitcoin,yenliangl/bitcoin,jnewbery/bitcoin,Xekyo/bitcoin,andreaskern/bitcoin,jnewbery/bitcoin,prusnak/bitcoin,apoelstra/bitcoin,fujicoin/fujicoin,sstone/bitcoin,instagibbs/bitcoin,ajtowns/bitcoin,namecoin/namecoin-core,alecalve/bitcoin,dscotese/bitcoin,mruddy/bitcoin,jambolo/bitcoin,prusnak/bitcoin,midnightmagic/bitcoin,instagibbs/bitcoin,midnightmagic/bitcoin,jnewbery/bitcoin,rnicoll/bitcoin,anditto/bitcoin,tecnovert/particl-core,mruddy/bitcoin,EthanHeilman/bitcoin,bitcoinsSG/bitcoin,sipsorcery/bitcoin,instagibbs/bitcoin,rnicoll/dogecoin,qtumproject/qtum,domob1812/namecore,MarcoFalke/bitcoin,instagibbs/bitcoin,MarcoFalke/bitcoin,qtumproject/qtum,particl/particl-core,sstone/bitcoin,ElementsProject/elements,GroestlCoin/GroestlCoin,bitcoinsSG/bitcoin