[wallet] Add logging to MarkReserveKeysAsUsed

Github-Pull: #11044
Rebased-From: 67ceff4039
Tree-SHA512: 850c5b1010c84e164edf24a83ae36e46309b2eb7a67854bad509265ed590ba67d5f743a8416590da6ecca85fe4bda7f20e8c3152e422638eb7898db11a416af7

src/wallet/wallet.cpp

@@ -3659,6 +3659,7 @@ void CWallet::MarkReserveKeysAsUsed(int64_t keypool_id)
             m_pool_key_to_index.erase(keypool.vchPubKey.GetID());
         }
         walletdb.ErasePool(index);
+        LogPrintf("keypool index %d removed\n", index);
         it = setKeyPool->erase(it);
     }
 }