Don't launch a coroutine job if no jobs to cancel

Flag: com.android.launcher3.enable_coroutine_threading_improvements
Bug: 417598777
Test: Presubmits
Change-Id: I474e3e12faf2886b593571e9625a1d16df742c0d

quickstep/src/com/android/quickstep/views/TaskView.kt

@@ -952,7 +952,9 @@ constructor(
             // onAttach or another moment in the lifecycle.
             val coroutineJobsToCancel = coroutineJobs.toList()
             coroutineJobs.clear()
-            if (enableCoroutineThreadingImprovements() && coroutineJobsToCancel.isNotEmpty()) {
+            if (coroutineJobsToCancel.isEmpty()) return
+
+            if (enableCoroutineThreadingImprovements()) {
                 // TODO(b/391842220): This should ideally be handled in the completion block of the
                 //  jobs above to be cancelled.
                 taskContainers.forEach {