wallet: Wallets without private keys cannot grind R

src/wallet/wallet.cpp

@@ -4038,7 +4038,7 @@ util::Result<void> CWallet::ApplyMigrationData(WalletBatch& local_wallet_batch,
 
 bool CWallet::CanGrindR() const
 {
-    return !IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER);
+    return !IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
 }
 
 bool DoMigration(CWallet& wallet, WalletContext& context, bilingual_str& error, MigrationResult& res) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)