deadlock caused by calling SetOptions() in OnStallConditionsChanged()

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Expected behavior

Exepct to see explicit comment on EventListener::OnStallConditionsChanged() callback mentioning SetOptions() cannot be used to avoid deadlock.

Actual behavior

Observed deadlock caused by calling WriteOptions() in OnStallConditionsChanged(). BackgroundCallFlush() => SuperVersionContext::Clean() => OnStallConditionsChanged() => WriteOptionsFile() => WriteThread::EnterUnbatched() => WriteThread::LinkOne() => wait for stall WriteImpl() => PreprocessWrite() => DelayWrite() => wait for stall

Steps to reproduce the behavior

• Override EventListener::OnStallConditionsChanged() to call DB::SetOptions().
• Create a write stall.