message: Call HandleFullyConfirmedBlock when ChainLocks are enabled but not enforced
  Otherwise IS locks never get removed before DIP8 activates via BIP9.
diff: @@ -818,7 +818,10 @@ void CInstantSendManager::NotifyChainLock(const CBlockIndex* pindexChainLock)
  void CInstantSendManager::UpdatedBlockTip(const CBlockIndex* pindexNew)
  {
  - if (sporkManager.IsSporkActive(SPORK_19_CHAINLOCKS_ENABLED)) {
  + // TODO remove this after DIP8 has activated
  + bool fDIP0008Active = VersionBitsState(pindexNew->pprev, Params().GetConsensus(), Consensus::DEPLOYMENT_DIP0008, versionbitscache) == THRESHOLD_ACTIVE;
  +
  + if (sporkManager.IsSporkActive(SPORK_19_CHAINLOCKS_ENABLED) && fDIP0008Active) {
  // Nothing to do here. We should keep all islocks and let chainlocks handle them.
  return;
  }
  