Merge dashpay#6219: fix: correct is_snapshot_cs in VerifyDB

bf377d4 fix: correct is_snapshot_cs in VerifyDB (James O'Beirne)

Pull request description:

  ## Issue being fixed or feature implemented
  Flag `is_snapshot_cs` has been inverted in bitcoin#21584

  Discovered during investigation of issue:
  ```
  Verifying last 6 blocks at level 3
  2024-08-14T14:51:55Z [0%]...*** Found EvoDB inconsistency, you must reindex to continue
  ```
  So far as code below does:
  ```
          if ((fPruneMode || is_snapshot_cs) && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
              // If pruning or running under an assumeutxo snapshot, only go
              // back as far as we have data.
              LogPrintf("VerifyDB(): block verification stopping at height %d (pruning, no data)\n", pindex->nHeight);
              break;
          }
  ```
  In case of missing data in evo db we will get instead of "block verification stopping at height" we may get data inconsistency issue.

  ## What was done?
  Inverted condition back (same fix in bitcoin#27596)

  ## How Has This Been Tested?
  Unit/functional tests doesn't cover it, but they do no fail after fix.

  ## 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

ACKs for top commit:
  UdjinM6:
    utACK bf377d4
  PastaPastaPasta:
    utACK bf377d4

Tree-SHA512: ac21e6db6e23c4c7dc150fb16171aef47c9f42c29466b403bca7d56ed6faa2fccc41df92e1fabec4d6e9fd56991e152dea168593a4550fc3583631a63009c27f

src/validation.cpp

@@ -4678,7 +4678,7 @@ bool CVerifyDB::VerifyDB(
     int reportDone = 0;
     LogPrintf("[0%%]..."); /* Continued */
 
-    const bool is_snapshot_cs{!chainstate.m_from_snapshot_blockhash};
+    const bool is_snapshot_cs{chainstate.m_from_snapshot_blockhash};
 
     for (pindex = chainstate.m_chain.Tip(); pindex && pindex->pprev; pindex = pindex->pprev) {
         const int percentageDone = std::max(1, std::min(99, (int)(((double)(chainstate.m_chain.Height() - pindex->nHeight)) / (double)nCheckDepth * (nCheckLevel >= 4 ? 50 : 100))));