replay: Deflake TestCompactionsQuiesce by waiting for sstable copy

All the replay datadriven tests wait for all enqueued sstables
to finish copying to the collection directory before we terminate
the workload collector. The one exception is TestCompactionsQuiesce
which currently calls the Stop() method even if there are
sstables waiting to be copied. This change delays the call to Stop()
until all enqueued sstables have been copied over.

Fixes #2833.

replay/replay_test.go

@@ -571,7 +571,7 @@ func buildHeavyWorkload(t *testing.T) vfs.FS {
 		require.NoError(t, b.Commit(pebble.NoSync))
 		require.NoError(t, d.Flush())
 	}
-	wc.Stop()
+	wc.WaitAndStop()
 
 	defer d.Close()
 	return destFS

replay/workload_capture.go

@@ -383,6 +383,18 @@ func (w *WorkloadCollector) Start(destFS vfs.FS, destPath string) {
 	go w.copyFiles()
 }
 
+// WaitAndStop waits for all enqueued sstables to be copied over, and then
+// calls Stop. Gracefully ensures that all sstables referenced in the collected
+// manifest's latest version edit will exist in the copy directory.
+func (w *WorkloadCollector) WaitAndStop() {
+	w.mu.Lock()
+	for w.mu.tablesEnqueued != w.mu.tablesCopied {
+		w.mu.copyCond.Wait()
+	}
+	w.mu.Unlock()
+	w.Stop()
+}
+
 // Stop stops collection of the workload.
 func (w *WorkloadCollector) Stop() {
 	w.mu.Lock()