wallet2: fix cold signing using non padded bulletproofs

This code was deciding which bulletproof configuration to use
based on ptx which weren't created yet.

src/wallet/wallet2.cpp

@@ -5563,10 +5563,7 @@ bool wallet2::sign_tx(unsigned_tx_set &exported_txs, std::vector<wallet2::pendin
     rct::RangeProofType range_proof_type = rct::RangeProofBorromean;
     if (sd.use_bulletproofs)
     {
-      range_proof_type = rct::RangeProofBulletproof;
-      for (const rct::Bulletproof &proof: ptx.tx.rct_signatures.p.bulletproofs)
-        if (proof.V.size() > 1)
-          range_proof_type = rct::RangeProofPaddedBulletproof;
+      range_proof_type = rct::RangeProofPaddedBulletproof;
     }
     crypto::secret_key tx_key;
     std::vector<crypto::secret_key> additional_tx_keys;