Intent of TestGetActivityHeartbeatTimeout_WithHeartbeat_Started_NoHeartbeat

All 5 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 5 tests
- server/ 5 tests
  - service/ 5 tests
    
    history/ 5 tests
    
    workflow/ 5 tests
    
    TestTimerSequenceSuite/ 5 tests
    
    go.temporal.io/server/service/history/workflow/TestTimerSequenceSuite/TestCreateNextActivityTimer_HeartbeatTimer_AfterWorkflowExpiry Inherited TestCreateNextActivityTimer_HeartbeatTimer_AfterWorkflowExpiry
    
    go.temporal.io/server/service/history/workflow/TestTimerSequenceSuite/TestCreateNextActivityTimer_HeartbeatTimer_BeforeWorkflowExpiry Inherited TestCreateNextActivityTimer_HeartbeatTimer_NoWorkflowExpiry, TestCreateNextActivityTimer_HeartbeatTimer_BeforeWorkflowExpiry
    
    go.temporal.io/server/service/history/workflow/TestTimerSequenceSuite/TestCreateNextActivityTimer_HeartbeatTimer_NoWorkflowExpiry Inherited TestCreateNextActivityTimer_HeartbeatTimer_NoWorkflowExpiry, TestCreateNextActivityTimer_HeartbeatTimer_BeforeWorkflowExpiry
    
    go.temporal.io/server/service/history/workflow/TestTimerSequenceSuite/TestGetActivityHeartbeatTimeout_WithHeartbeat_Started_NoHeartbeat Introduced here
    
    go.temporal.io/server/service/history/workflow/TestTimerSequenceSuite/TestLoadAndSortActivityTimers_One_Scheduled_Started_WithHeartbeatTimeout Inherited TestLoadAndSortActivityTimers_One_Scheduled_Started_WithHeartbeatTimeout