Merge bitcoin/bitcoin#28833: wallet: refactor: remove unused SignatureData instances in spkm's FillPSBT methods

e2ad343 wallet: remove unused `SignatureData` instances in spkm's `FillPSBT` methods (Sebastian Falbesoner)

Pull request description:

  These are filled with signature data from a PSBT input, but not used anywhere after, hence they can be removed. Note that the same code is in the `SignPSBTInput` function where the `sigdata` result is indeed used.

ACKs for top commit:
  achow101:
    ACK e2ad343
  brunoerg:
    crACK e2ad343

Tree-SHA512: f0cabcc000bcea6bc7d7ec9d3be2e2a8accbdbffbe35252250ea2305b65a5813fde2b8096fbdd2c7cccdf417ea285183dc325fc2d210d88bce62978ce642930e

Author: achow101

src/wallet/scriptpubkeyman.cpp

@@ -652,8 +652,6 @@ TransactionError LegacyScriptPubKeyMan::FillPSBT(PartiallySignedTransaction& psb
             // There's no UTXO so we can just skip this now
             continue;
         }
-        SignatureData sigdata;
-        input.FillSignatureData(sigdata);
         SignPSBTInput(HidingSigningProvider(this, !sign, !bip32derivs), psbtx, i, &txdata, sighash_type, nullptr, finalize);
 
         bool signed_one = PSBTInputSigned(input);
@@ -2528,8 +2526,6 @@ TransactionError DescriptorScriptPubKeyMan::FillPSBT(PartiallySignedTransaction&
             // There's no UTXO so we can just skip this now
             continue;
         }
-        SignatureData sigdata;
-        input.FillSignatureData(sigdata);
 
         std::unique_ptr<FlatSigningProvider> keys = std::make_unique<FlatSigningProvider>();
         std::unique_ptr<FlatSigningProvider> script_keys = GetSigningProvider(script, /*include_private=*/sign);