flaky test TestSlotManagerInManager

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

3. What did you see instead (Required)

     manager.go:335: Unexpected call to *mock.MockTaskExecutor.Close([]) at pkg/disttask/framework/taskexecutor/manager.go:335 because: there are no expected calls of the method "Close" for that receiver
    manager_test.go:375: 
        	Error Trace:	pkg/disttask/framework/taskexecutor/manager_test.go:375
        	Error:      	Should be true
        	Test:       	TestSlotManagerInManager
    controller.go:243: missing call(s) to *mock.MockTaskExecutor.Close() pkg/disttask/framework/taskexecutor/manager_test.go:370
    controller.go:243: aborting test due to missing call(s)
--- FAIL: TestSlotManagerInManager (0.31s) 

https://tiprow.hawkingrei.com/view/gs/pingcapprow/pr-logs/pull/pingcap_tidb/52226/fast_test_tiprow/1773735551308926976

4. What is your TiDB version? (Required)