message: [zPIV][Cleanup] Remove non-public zerocoin spend checks in ATMP
  Now that activation height has passed, remove
  CheckPublicCoinSpendEnforced and simply reject any non-public zerocoin
  spend in AcceptToMemoryPool, without doing any further validation.
diff: @@ -1236,21 +1236,11 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState& state, const CTransa
  //Check for double spending of serial #'s
  for (const CTxIn& txIn : tx.vin) {
  - // Only allow for zc spends inputs
  - bool isPublicSpend = txIn.IsZerocoinPublicSpend();
  - bool isPrivZerocoinSpend = txIn.IsZerocoinSpend();
  - if (!isPrivZerocoinSpend && !isPublicSpend) {
  - return state.Invalid(error("%s: failed for tx %s, every input must be a zcspend or zcpublicspend",
  + // Only allow for public zc spends inputs
  + if (!txIn.IsZerocoinPublicSpend())
  + return state.Invalid(error("%s: failed for tx %s, every input must be a zcpublicspend",
  __func__, tx.GetHash().GetHex()), REJECT_INVALID, "bad-txns-invalid-zpiv");
  - }
  -
  - // Check enforcement
  - if (!CheckPublicCoinSpendEnforced(chainActive.Height(), isPublicSpend)){
  - return state.Invalid(error("%s: CheckPublicCoinSpendEnforced failed for tx %s",
  - __func__, tx.GetHash().GetHex()), REJECT_INVALID, "bad-txns-invalid-zpiv");
  - }
  - if (isPublicSpend) {
  libzerocoin::ZerocoinParams* params = Params().Zerocoin_Params(false);
  PublicCoinSpend publicSpend(params);
  if (!ZPIVModule::ParseZerocoinPublicSpend(txIn, tx, state, publicSpend)){
  @@ -1266,13 +1256,6 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState& state, const CTransa
  __func__, publicSpend.getVersion(), CurrentPublicCoinSpendVersion()), REJECT_INVALID, "bad-txns-invalid-zpiv");
  }
  - } else {
  - libzerocoin::CoinSpend spend = TxInToZerocoinSpend(txIn);
  - if (!ContextualCheckZerocoinSpend(tx, &spend, chainActive.Tip(), 0))
  - return state.Invalid(error("%s: ContextualCheckZerocoinSpend failed for tx %s",
  - __func__, tx.GetHash().GetHex()), REJECT_INVALID, "bad-txns-invalid-zpiv");
  - }
  -
  }
  } else {
  LOCK(pool.cs);
  