TestTaskManager_CreateExecDeleteTask is flaky

[kzys]

https://github.com/firecracker-microvm/firecracker-containerd/runs/5250770611?check_suite_focus=true

 --- FAIL: TestTaskManager_CreateExecDeleteTask (0.20s)
    task_test.go:459: 
        	Error Trace:	task_test.go:459
        	Error:      	"[&WaitRequest{ID:fakeTask,ExecID:,XXX_unrecognized:[],}]" should have 2 item(s), but has 1
        	Test:       	TestTaskManager_CreateExecDeleteTask
        	Messages:   	Wait called unexpected number of times for "fakeTask"