message: Delete Util::StringPrintf.
  All the calls were migrated to absl::StrFormat and, hence, it is no longer
  necessary.
diff: @@ -280,12 +280,6 @@ class Util {
  // in the range of Android Emoji PUA.
  static bool IsAndroidPuaEmoji(absl::string_view s);
  - template <typename... Args>
  - static std::string StringPrintf(const absl::FormatSpec<Args...> &format,
  - Args &&...args) {
  - return absl::StrFormat(format, std::forward<Args>(args)...);
  - }
  -
  // Chop the return characters (i.e. '\n' and '\r') at the end of the
  // given line.
  static bool ChopReturns(std::string *line);
  