wallet: remove redundant Assert call when block is disconnected

It was highlighted in a PR discussion previously that the recently
moved `Assert` macro call inside the block disconnected loop had
been redundant for quite a while because of the presence of the
`assert` macro call at the start of the function. Therefore, it
is removed now.

refs #bitcoin/bitcoin#31757 (comment)

Author: rkrux

src/wallet/wallet.cpp

@@ -1549,7 +1549,7 @@ void CWallet::blockDisconnected(const interfaces::BlockInfo& block)
     int disconnect_height = block.height;
 
     for (size_t index = 0; index < block.data->vtx.size(); index++) {
-        const CTransactionRef& ptx = Assert(block.data)->vtx[index];
+        const CTransactionRef& ptx = block.data->vtx[index];
         // Coinbase transactions are not only inactive but also abandoned,
         // meaning they should never be relayed standalone via the p2p protocol.
         SyncTransaction(ptx, TxStateInactive{/*abandoned=*/index == 0});