check fail in http_client_pool

[romange]

F20250224 20:20:00.057886  2843 https_client_pool.cc:37] Check failed: unsigned(existing_handles_) == available_handles_.size() (1 vs. 0)
*** Check failure stack trace: ***
    @     0x5c295ca97803  google::LogMessage::Fail()
    @     0x5c295ca97749  google::LogMessage::SendToLog()
    @     0x5c295ca96efc  google::LogMessage::Flush()
    @     0x5c295ca9aff4  google::LogMessageFatal::~LogMessageFatal()
    @     0x5c295c97e505  util::http::ClientPool::~ClientPool()
    @     0x5c295c9522d5  util::cloud::OpenWriteGcsFile()
    @     0x5c295c324da4  dfly::detail::GcsSnapshotStorage::OpenWriteFile()
    @     0x5c295c30c597  dfly::detail::RdbSnapshot::Start()
    @     0x5c295c30daa9  dfly::detail::SaveStagesController::SaveDfsSingle()
    @     0x5c295c30d8ae  dfly::detail::SaveStagesController::SaveDfs()