ledger: fix Ledger_Client_Legacy.sign_transaction()

fix signing txs when using old "bitcoin app" (pre-2.1) on the ledger device

```
 33.36 | W | transaction | heyheyhey. cp1. include_sigs=True force_legacy=False use_segwit_ser=True
 33.36 | W | transaction | heyheyhey. cp2. branch1
 33.37 | E | plugins.ledger.ledger |
Traceback (most recent call last):
  File "...\electrum\electrum\plugins\ledger\ledger.py", line 669, in sign_transaction
    rawTx = tx.serialize_to_network()
  File "...\electrum\electrum\transaction.py", line 945, in serialize_to_network
    witness = ''.join(self.serialize_witness(x, estimate_size=estimate_size) for x in inputs)
  File "...\electrum\electrum\transaction.py", line 945, in <genexpr>
    witness = ''.join(self.serialize_witness(x, estimate_size=estimate_size) for x in inputs)
  File "...\electrum\electrum\transaction.py", line 839, in serialize_witness
    sol = desc.satisfy(allow_dummy=estimate_size, sigdata=txin.part_sigs)
  File "...\electrum\electrum\descriptor.py", line 378, in satisfy
    sol = self._satisfy_inner(sigdata=sigdata, allow_dummy=allow_dummy)
  File "...\electrum\electrum\descriptor.py", line 574, in _satisfy_inner
    raise MissingSolutionPiece(f"no sig for {pubkey.hex()}")
electrum.descriptor.MissingSolutionPiece: no sig for 033e92e55923ea25809790f292ee9bd410355ee02492472d9a1ff1b364874d0679
 33.38 | I | plugins.ledger.ledger | no sig for 033e92e55923ea25809790f292ee9bd410355ee02492472d9a1ff1b364874d0679
```

fixes https://github.com/spesmilo/electrum/issues/8365
regression from https://github.com/spesmilo/electrum/pull/8230

electrum/plugins/ledger/ledger.py

@@ -666,7 +666,7 @@ class Ledger_Client_Legacy(Ledger_Client):
             # Sign all inputs
             firstTransaction = True
             inputIndex = 0
-            rawTx = tx.serialize_to_network()
+            rawTx = tx.serialize_to_network(include_sigs=False)
             if self.is_hw1():
                 self.dongleObject.enableAlternate2fa(False)
             if segwitTransaction: