Merge dashpay#6647: perf: remove extra lookup to map during BuildNewListFromBlock

4a43c62 fix: clearify nullptr value in case of payee is nullptr (Konstantin Akimov)
b375c38 perf: remove extra lookup to map during BuildNewListFromBlock (Konstantin Akimov)

Pull request description:

  ## What was done?
  Removed double lookup in a map with all masternodes: with `HasMN` and `GetMN`.

  ## How Has This Been Tested?
  Run unit/functional tests

  ## Breaking Changes
  N/A

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK 4a43c62
  PastaPastaPasta:
    utACK 4a43c62

Tree-SHA512: 82d67995c8e5dd6c28668cf8ac583f08468c1607143d0676db358c1fba5fd824512ae374b9e5bc13058b061f1695b7eac1ff8f149d69f553daa6b4968fb8fa25

Author: PastaPastaPasta

src/evo/deterministicmns.cpp

@@ -888,10 +888,7 @@ bool CDeterministicMNManager::BuildNewListFromBlock(const CBlock& block, gsl::no
 
     // The payee for the current block was determined by the previous block's list, but it might have disappeared in the
     // current block. We still pay that MN one last time, however.
-    if (payee && newList.HasMN(payee->proTxHash)) {
-        auto dmn = newList.GetMN(payee->proTxHash);
-        // HasMN has reported that GetMN should succeed, enforce that.
-        assert(dmn);
+    if (auto dmn = payee ? newList.GetMN(payee->proTxHash) : nullptr) {
         auto newState = std::make_shared<CDeterministicMNState>(*dmn->pdmnState);
         newState->nLastPaidHeight = nHeight;
         // Starting from v19 and until MNRewardReallocation, EvoNodes will be paid 4 blocks in a row