Async wf consumer manager should watch its enabled/disabled state instead of relying on restart

[taylanisikdemir]

What changed?
Worker creates the ConsumerManager only if worker.enableAsyncWorkflowConsumption is set to true. Enabling this property at runtime has no effect. This means workers have to be restarted after dynamic property changes which is not ideal.
Similarly disabling this property doesn't stop consumer manager and requires restart to take effect. In emergency situations it might be handy to quickly stop the async request queue consumption.

Why?
Avoid restarts for enabling/disabling ConsumerManager.

How did you test it?
New unit test which enables, disables and re-enables consumer manager.

[coveralls]

Pull Request Test Coverage Report for Build 018f3b3c-928c-43e0-b33d-857843399566

Details

• 44 of 49 (89.8%) changed or added relevant lines in 2 files are covered.
• 72 unchanged lines in 10 files lost coverage.
• Overall coverage decreased (-0.009%) to 68.122%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
service/worker/asyncworkflow/async_workflow_consumer_manager.go	44	46	95.65%
service/worker/service.go	0	3	0.0%

Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	2	89.05%
service/history/task/transfer_active_task_executor.go	2	72.9%
service/matching/taskListManager.go	2	81.16%
common/membership/hashring.go	2	84.69%
common/persistence/historyManager.go	2	66.67%
common/persistence/statsComputer.go	3	96.07%
common/task/fifo_task_scheduler.go	4	85.57%
service/history/task/fetcher.go	4	86.08%
service/history/task/task_util.go	20	70.57%
service/history/execution/mutable_state_task_refresher.go	31	56.65%

Totals
Change from base Build 018f3ade-e831-49de-8d50-1cfcf0e4bf6a:	-0.009%
Covered Lines:	100070
Relevant Lines:	146898

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💛 - Coveralls