message: Fix banning when local node doesn't have the vvec
  When ProcessMessageBatchedSigShares returns false, it's interpreted as
  if an invalid/malicious message was received, causing a ban. So, we should
  return "!ban" instead of just "ban".
diff: @@ -411,7 +411,7 @@ bool CSigSharesManager::ProcessMessageBatchedSigShares(CNode* pfrom, const CBatc
  bool ban = false;
  if (!PreVerifyBatchedSigShares(pfrom->id, sessionInfo, batchedSigShares, ban)) {
  - return ban;
  + return !ban;
  }
  std::vector<CSigShare> sigShares;
  