Fix: Retiming keys are not visble

Caused by checking if retiming mode is active to prevent executing
unnecessary code paths.

Check if keys exist instead.

Pull Request: https://projects.blender.org/blender/blender/pulls/124840

source/blender/editors/space_sequencer/sequencer_retiming_draw.cc

@@ -244,7 +244,7 @@ static bool can_draw_retiming(const TimelineDrawContext *timeline_ctx,
     return false;
   }
 
-  if (!SEQ_retiming_is_active(strip_ctx.seq)) {
+  if (SEQ_retiming_keys_count(strip_ctx.seq) == 0) {
     return false;
   }