wallet2: remove redundant chacha key generation in store_keys

src/wallet/wallet2.cpp

@@ -3144,7 +3144,6 @@ bool wallet2::store_keys(const std::string& keys_file_name, const epee::wipeable
   account_data = buffer.GetString();
 
   // Encrypt the entire JSON object.
-  crypto::generate_chacha_key(password.data(), password.size(), key, m_kdf_rounds);
   std::string cipher;
   cipher.resize(account_data.size());
   keys_file_data.iv = crypto::rand<crypto::chacha_iv>();