message: [mempool] Remove error suppression on upgrade
  In 0.21, we added unbroadcast txids to mempool.dat. Commit
  added a try-block to prevent throwing a "failed to deserialize mempool data"
  error when a user upgrades from 0.21 to 0.22. This exception handling is no
  longer useful, so now we can remove it.
diff: @@ -4731,15 +4731,9 @@ bool LoadMempool(CTxMemPool& pool)
  pool.PrioritiseTransaction(i.first, i.second);
  }
  - // TODO: remove this try except in v0.22
  std::set<uint256> unbroadcast_txids;
  - try {
  file >> unbroadcast_txids;
  unbroadcast = unbroadcast_txids.size();
  - } catch (const std::exception&) {
  - // mempool.dat files created prior to v0.21 will not have an
  - // unbroadcast set. No need to log a failure if parsing fails here.
  - }
  for (const auto& txid : unbroadcast_txids) {
  // Ensure transactions were accepted to mempool then add to
  // unbroadcast set.
  