wallet: fix sendall creates tx that fails tx-size check

The `sendall` RPC doesn't use `CreateTransactionInternal`as the rest of
the wallet RPCs and it never checks against the tx-size mempool limit.
Add a check for tx-size as well as test coverage for that case.

src/wallet/rpc/spend.cpp

@@ -1414,6 +1414,11 @@ RPCHelpMan sendall()
                 }
             }
 
+            // If this transaction is too large, e.g. because the wallet has many UTXOs, it will be rejected by the node's mempool.
+            if (tx_size.weight > MAX_STANDARD_TX_WEIGHT) {
+                throw JSONRPCError(RPC_WALLET_ERROR, "Transaction too large.");
+            }
+
             CAmount output_amounts_claimed{0};
             for (const CTxOut& out : rawTx.vout) {
                 output_amounts_claimed += out.nValue;