When destroying or resetting an open RecordWriter which uses parall…

…elism,

do not interrupt background work. Wait for it to complete.

There might be a pending `FutureFlush()` in the queue of requests, which means
that pending writes before it are not necessarily irrelevant. The caller can
expect the flush to be eventually finished, which is as good as closing.

PiperOrigin-RevId: 624863444

riegeli/records/record_writer.cc

@@ -628,11 +628,7 @@ inline RecordWriterBase::ParallelWorker::ParallelWorker(
 }
 
 RecordWriterBase::ParallelWorker::~ParallelWorker() {
-  if (ABSL_PREDICT_FALSE(state_.is_open())) {
-    // Ask the chunk writer thread to stop working and exit.
-    ParallelWorker::FailWithoutAnnotation(absl::CancelledError());
-    Done();
-  }
+  if (ABSL_PREDICT_FALSE(state_.is_open())) Done();
 }
 
 void RecordWriterBase::ParallelWorker::Done() {