message: timeformatter static-init
  Fix flaky h1_capture_persistent_fuzz_test at my branch
  Risk Level: LOW
diff: @@ -416,9 +416,11 @@ std::string StringUtil::escape(const std::string& source) {
  return ret;
  }
  -std::string AccessLogDateTimeFormatter::fromTime(const SystemTime& system_time) {
  - static const std::string DefaultDateFormat = "%Y-%m-%dT%H:%M:%E3SZ";
  +const std::string& getDefaultDateFormat() {
  + CONSTRUCT_ON_FIRST_USE(std::string, "%Y-%m-%dT%H:%M:%E3SZ");
  +}
  +std::string AccessLogDateTimeFormatter::fromTime(const SystemTime& system_time) {
  struct CachedTime {
  std::chrono::seconds epoch_time_seconds;
  std::string formatted_time;
  @@ -432,8 +434,8 @@ std::string AccessLogDateTimeFormatter::fromTime(const SystemTime& system_time)
  std::chrono::duration_cast<std::chrono::seconds>(epoch_time_ms);
  if (cached_time.formatted_time.empty() || cached_time.epoch_time_seconds != epoch_time_seconds) {
  - cached_time.formatted_time =
  - absl::FormatTime(DefaultDateFormat, absl::FromChrono(system_time), absl::UTCTimeZone());
  + cached_time.formatted_time = absl::FormatTime(
  + getDefaultDateFormat(), absl::FromChrono(system_time), absl::UTCTimeZone());
  cached_time.epoch_time_seconds = epoch_time_seconds;
  } else {
  // Overwrite the digits in the ".000Z" at the end of the string with the
  