test: Add test for conflicted wallet tx notifications
test: Add test for conflicted wallet tx notifications

Add test coverage for conflicted wallet transaction notifications so we improve
current behavior and avoid future regressions

https://github.com/bitcoin/bitcoin/pull/9240 - accidental break
https://github.com/bitcoin/bitcoin/issues/9479 - bug report
https://github.com/bitcoin/bitcoin/pull/9371 - fix
https://github.com/bitcoin/bitcoin/pull/16624 - accidental break
https://github.com/bitcoin/bitcoin/issues/18325 - bug report
https://github.com/bitcoin/bitcoin/pull/18600 - potential fix

Github-Pull: #18878
Rebased-From: f963a680515eda66429b3d1537a7baf281ab9283

vertcoin/vertcoin,GroestlCoin/bitcoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,qtumproject/qtum,ahmedbodi/vertcoin,monacoinproject/monacoin,vertcoin/vertcoin,DigitalPandacoin/pandacoin,vertcoin/vertcoin,qtumproject/qtum,GroestlCoin/GroestlCoin,GroestlCoin/GroestlCoin,qtumproject/qtum,GroestlCoin/GroestlCoin,qtumproject/qtum,monacoinproject/monacoin,ahmedbodi/vertcoin,peercoin/peercoin,DigitalPandacoin/pandacoin,ahmedbodi/vertcoin,ahmedbodi/vertcoin,monacoinproject/monacoin,monacoinproject/monacoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,GroestlCoin/GroestlCoin,peercoin/peercoin,DigitalPandacoin/pandacoin,peercoin/peercoin,GroestlCoin/bitcoin,qtumproject/qtum,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,qtumproject/qtum,monacoinproject/monacoin,GroestlCoin/bitcoin,vertcoin/vertcoin,monacoinproject/monacoin,qtumproject/qtum,peercoin/peercoin,ahmedbodi/vertcoin,GroestlCoin/bitcoin,peercoin/peercoin,vertcoin/vertcoin,vertcoin/vertcoin,peercoin/peercoin,DigitalPandacoin/pandacoin