message: A little shard of cl/401238122. Replace the deprecated crypto::tink::util::Status::error_message() method with its absl-compatible version crypto::tink::util::Status::message().
  This CL is a part of Tink migration to using absl::Status{,Or}.
diff: @@ -139,7 +139,7 @@ MATCHER_P(StatusIs, code,
  // use code() after all StatusIs usages are migrated to use absl::StatusCode.
  MATCHER_P2(StatusIs, code, message_matcher, "") {
  return (arg.code() == static_cast<absl::StatusCode>(code)) &&
  - testing::Matches(message_matcher)(arg.error_message());
  + testing::Matches(message_matcher)(std::string(arg.message()));
  }
  // Matches a Keyset::Key with `key`.
  