tracing: enable fine-grained redactability for unstructured events

This enables finer-grain redraction for unstructured events in traces.
See #103883 for a discussion. (This can be reverted in case
performance is found to be unacceptable.)

Release note: None

pkg/util/tracing/tracer.go

@@ -108,11 +108,8 @@ const (
 var enableTraceRedactable = settings.RegisterBoolSetting(
 	settings.TenantWritable,
 	"trace.redactable.enabled",
-	"set to true to enable redactability for unstructured events "+
-		"in traces and to redact traces sent to tenants. "+
-		"Set to false to coarsely mark unstructured events as redactable "+
-		" and eliminate them from tenant traces.",
-	false,
+	"set to true to enable finer-grain redactability for unstructured events in traces",
+	true,
 )
 
 var enableNetTrace = settings.RegisterBoolSetting(