Merge #19468: refactor: Drop unused CDBWrapper methods

4b5ac25881 Drop unused CDBWrapper methods (Hennadii Stepanov)

Pull request description:

  `CDBWrapper::Flush()` and `CDBWrapper::Sync()` are not used in the code.

ACKs for top commit:
  promag:
    ACK 4b5ac25881.
  laanwj:
    ACK 4b5ac25881

Tree-SHA512: 06115c59e75995d496173a64ceea1b9bb1b4fe3eac8bf4f59df68b87b112b5b3e8065298dcd5c4c7408544f76ee62922325acc2208619d830fd5dbb420cdda5c

src/dbwrapper.h

@@ -292,18 +292,6 @@ public:
     // Get an estimate of LevelDB memory usage (in bytes).
     size_t DynamicMemoryUsage() const;
 
-    // not available for LevelDB; provide for compatibility with BDB
-    bool Flush()
-    {
-        return true;
-    }
-
-    bool Sync()
-    {
-        CDBBatch batch(*this);
-        return WriteBatch(batch, true);
-    }
-
     CDBIterator *NewIterator()
     {
         return new CDBIterator(*this, pdb->NewIterator(iteroptions));