test: Add unregister_validation_interface_race test
test: Add unregister_validation_interface_race test

This commit is (intentionally) adding a broken test. The test is broken
because it registering a subscriber object that can go out of scope
while events are still being sent.

To run the broken test and reproduce the bug:
  - Remove comment /** and */
  - ./configure --with-sanitizers=address
  - export ASAN_OPTIONS=detect_leaks=0
  - make
  - while ./src/test/test_bitcoin -t validationinterface_tests/unregister_validation_interface_race --catch_system_errors=no  ; do true; done

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