asim: set settingsGen.Settings.OnRecording if tr is enabled

Previously, asim was setting settingsGen.Settings.OnRecording on
if tr is disabled which was unintentional. This commit fixes it
to set OnRecording when tr is enabled instead.

Author: wenyihu6

pkg/kv/kvserver/asim/tests/datadriven_simulation_test.go

@@ -577,7 +577,7 @@ func TestDataDriven(t *testing.T) {
 							seedGen := rand.New(rand.NewSource(seed))
 							for sample := 0; sample < samples; sample++ {
 								tr := makeTraceHelper(rewrite, plotDir, testName, sample+1, duration)
-								if !tr.enabled {
+								if tr.enabled {
 									// Only populate OnRecording if we're going to save the results.
 									// That way, we avoid creating trace spans during normal test runs.
 									settingsGen.Settings.OnRecording = func(storeID int64, atDuration time.Duration, rec tracingpb.Recording) {