message: refactor: Drop call to GetWalletEnv in wallet salvage code
  No observable change in behavior. This just avoids a redundant environment
  lookup. Motivation is to be able to simplify the GetWalletEnv implementation in
  an upcoming commit.
diff: @@ -32,8 +32,9 @@ bool RecoverDatabaseFile(const fs::path& file_path, bilingual_str& error, std::v
  std::unique_ptr<WalletDatabase> database = MakeDatabase(file_path, options, status, error);
  if (!database) return false;
  - std::string filename;
  - std::shared_ptr<BerkeleyEnvironment> env = GetWalletEnv(file_path, filename);
  + BerkeleyDatabase& berkeley_database = static_cast<BerkeleyDatabase&>(*database);
  + std::string filename = berkeley_database.Filename();
  + std::shared_ptr<BerkeleyEnvironment> env = berkeley_database.env;
  if (!env->Open(error)) {
  return false;
  