fix: Update conditions and unify calculations for the number of "winners" to skip when mixing (#5532)

## Issue being fixed or feature implemented
`JoinExistingQueue` was tweaked for regtest/devnets in #4394 but we have
"skipping winners" logic in `StartNewQueue` too. We should also use
weighted count when checking "skip winners" conditions.

## What was done?
Add a helper to calculate the number and use it in both methods. Adjust
logic.

## How Has This Been Tested?
Running a local mixing node on devnet ~- no "skipping winners" in logs
anymore.~ and testnet

## 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

src/coinjoin/client.cpp

@@ -1042,18 +1042,20 @@ CDeterministicMNCPtr CCoinJoinClientManager::GetRandomNotUsedMasternode()
     return nullptr;
 }
 
+static int WinnersToSkip()
+{
+    return (Params().NetworkIDString() == CBaseChainParams::DEVNET ||
+            Params().NetworkIDString() == CBaseChainParams::REGTEST)
+            ? 1 : 8;
+}
+
 bool CCoinJoinClientSession::JoinExistingQueue(CAmount nBalanceNeedsAnonymized, CConnman& connman)
 {
     if (!CCoinJoinClientOptions::IsEnabled()) return false;
     if (coinJoinClientQueueManager == nullptr) return false;
 
-    auto mnList = deterministicMNManager->GetListAtChainTip();
+    const auto mnList = deterministicMNManager->GetListAtChainTip();
-
+    const int nWeightedMnCount = mnList.GetValidWeightedMNsCount();
-    int winners_to_skip{8};
-
-    if (Params().NetworkIDString() == CBaseChainParams::DEVNET || Params().NetworkIDString() == CBaseChainParams::REGTEST) {
-        winners_to_skip = 0;
-    }
 
     // Look through the queues and see if anything matches
     CCoinJoinQueue dsq;
@@ -1066,7 +1068,7 @@ bool CCoinJoinClientSession::JoinExistingQueue(CAmount nBalanceNeedsAnonymized,
         }
 
         // skip next mn payments winners
-        if (dmn->pdmnState->nLastPaidHeight + int(mnList.GetValidMNsCount()) < mnList.GetHeight() + winners_to_skip) {
+        if (dmn->pdmnState->nLastPaidHeight + nWeightedMnCount < mnList.GetHeight() + WinnersToSkip()) {
             LogPrint(BCLog::COINJOIN, "CCoinJoinClientSession::JoinExistingQueue -- skipping winner, masternode=%s\n", dmn->proTxHash.ToString());
             continue;
         }
@@ -1113,8 +1115,9 @@ bool CCoinJoinClientSession::StartNewQueue(CAmount nBalanceNeedsAnonymized, CCon
     if (nBalanceNeedsAnonymized <= 0) return false;
 
     int nTries = 0;
-    auto mnList = deterministicMNManager->GetListAtChainTip();
+    const auto mnList = deterministicMNManager->GetListAtChainTip();
-    int nMnCount = mnList.GetValidMNsCount();
+    const int nMnCount = mnList.GetValidMNsCount();
+    const int nWeightedMnCount = mnList.GetValidWeightedMNsCount();
 
     // find available denominated amounts
     std::set<CAmount> setAmounts;
@@ -1138,7 +1141,7 @@ bool CCoinJoinClientSession::StartNewQueue(CAmount nBalanceNeedsAnonymized, CCon
         coinJoinClientManagers.at(mixingWallet.GetName())->AddUsedMasternode(dmn->collateralOutpoint);
 
         // skip next mn payments winners
-        if (dmn->pdmnState->nLastPaidHeight + nMnCount < mnList.GetHeight() + 8) {
+        if (dmn->pdmnState->nLastPaidHeight + nWeightedMnCount < mnList.GetHeight() + WinnersToSkip()) {
             LogPrint(BCLog::COINJOIN, "CCoinJoinClientSession::StartNewQueue -- skipping winner, masternode=%s\n", dmn->proTxHash.ToString());
             nTries++;
             continue;