refactor: enhance health check function and add comprehensive test coverage

- Updated GetHealthFn to return an error for better error handling and clarity.
- Introduced a new test file for schedule management, covering various endpoints including creation, retrieval, updating, and deletion of schedules.
- Added tests for task management, including task creation, retrieval, updating, and cancellation.
- Implemented utility tests for filtering and response generation to ensure consistent API behavior.
- Improved logging in the task scheduler service for better traceability.

core/task/scheduler/service.go

@@ -245,6 +245,7 @@ func newTaskSchedulerService() *Service {
 		interval:   5 * time.Second,
 		svr:        server.GetGrpcServer(),
 		handlerSvc: handler.GetTaskHandlerService(),
+		Logger:     utils.NewLogger("TaskScheduler"),
 	}
 }