Intent of does_nothing_when_no_pending_commands

All 3 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 3 tests
- server/ 3 tests
  - service/ 3 tests
    
    history/ 3 tests
    
    api/ 3 tests
    
    respondworkflowtaskcompleted/ 3 tests
    
    TestFlushWorkerCommandsTasks/ 3 tests
    
    go.temporal.io/server/service/history/api/respondworkflowtaskcompleted/TestFlushWorkerCommandsTasks/batches_commands_by_control_queue Inherited mutable_state_mock.go ×2
    
    go.temporal.io/server/service/history/api/respondworkflowtaskcompleted/TestFlushWorkerCommandsTasks/creates_separate_tasks_for_different_control_queues Inherited mutable_state_mock.go ×2
    
    go.temporal.io/server/service/history/api/respondworkflowtaskcompleted/TestFlushWorkerCommandsTasks/does_nothing_when_no_pending_commands Introduced here