Intent of when_ActivityTaskCompletedEvent_in_history_will_link_event_to_started

All 7 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 7 tests
- server/ 7 tests
  - service/ 7 tests
    
    history/ 7 tests
    
    TestEngineSuite/ 5 tests
    
    go.temporal.io/server/service/history/TestEngineSuite/TestRequestCancel_RespondWorkflowTaskCompleted_NoHeartBeat Inherited TestRequestCancel_RespondWorkflowTaskCompleted_NoHeartBeat
    
    go.temporal.io/server/service/history/TestEngineSuite/TestRequestCancel_RespondWorkflowTaskCompleted_Success Inherited TestRequestCancel_RespondWorkflowTaskCompleted_Success
    
    go.temporal.io/server/service/history/TestEngineSuite/TestRequestCancel_RespondWorkflowTaskCompleted_SuccessWithQueries Inherited TestRequestCancel_RespondWorkflowTaskCompleted_SuccessWithQueries
    
    go.temporal.io/server/service/history/TestEngineSuite/TestRespondActivityTaskCanceledById_Started Inherited TestRespondActivityTaskCanceledById_Started
    
    go.temporal.io/server/service/history/TestEngineSuite/TestRespondActivityTaskCanceled_Started Inherited TestRespondActivityTaskCanceled_Started
    
    historybuilder/ 2 tests
    
    TestHistoryBuilder_FlushBufferToCurrentBatch/ 1 test
    
    go.temporal.io/server/service/history/historybuilder/TestHistoryBuilder_FlushBufferToCurrentBatch/when_ActivityTaskCompletedEvent_in_history_will_link_event_to_started Introduced here
    
    TestHistoryBuilder_FlushBufferToCurrentBatch_WiringEvents/ 1 test
    
    go.temporal.io/server/service/history/historybuilder/TestHistoryBuilder_FlushBufferToCurrentBatch_WiringEvents/for_every_Activity_event_should_point_to_its_causal_event Inherited for_every_Activity_event_should_point_to_its_causal_event