[v0.14.0.x] Fix off-by-one error in InstantSend mining info removal when disconnecting blocks (#2951)
[v0.14.0.x] Fix off-by-one error in InstantSend mining info removal when disconnecting blocks (#2951)

* Refactor checks for disconnected blocks and conflicts in CInstantSendManager::SyncTransaction

* Fix off-by-one when calling RemoveInstantSendLockMined

nmarley/dash,nmarley/dash,nmarley/dash,dashpay/dash,UdjinM6/dash,thelazier/dash,thelazier/dash,thelazier/dash,UdjinM6/dash,UdjinM6/dash,thelazier/dash,UdjinM6/dash,ionomy/ion,dashpay/dash,dashpay/dash,thelazier/dash,ionomy/ion,ionomy/ion,dashpay/dash,ionomy/ion,ionomy/ion,ionomy/ion,nmarley/dash,nmarley/dash,nmarley/dash,nmarley/dash,UdjinM6/dash,dashpay/dash