rework on poller auto scaler (#1411)

Detailed Description

Improve performance of poller auto scaler by using more accurate scaling signals and several implementation changes.

Changes

New WorkerOptions AutoScalerOptions is introduced.
Several WorkerOptions are deprecated and become no-op.
read new signal (poller wait time) to scale
allow kill switching poller auto scaler from server
new implementation that makes scaling quicker to traffic change
removed no longer used autoscaler package completely (original implementation is over complicated)
Impact Analysis

Backward Compatibility: NO existing autoscaling will be stopped but this shall not have big impact since this feature was never rolled out in production. For OSS users, please follow the instructions below in rollout plan.
Forward Compatibility: Yes, introduce new
Testing Plan

Unit Tests: Yes
Persistence Tests: Not related
Integration Tests: No
Compatibility Tests: No, because it's autoscaler is a feature that was not rolled out in production.
Rollout Plan

What is the rollout plan?
For Uber services, standard client release steps
For OSS users, turn off autoscaler feature first before the client upgrade.

Does the order of deployment matter? No

Is it safe to rollback? Does the order of rollback matter? Yes

Is there a kill switch to mitigate the impact immediately? Yes, the new autoscaler feature is an opt-in feature.

Author: shijiesheng

internal/common/autoscaler/autoscaler.go

@@ -114,4 +114,7 @@ const (
 	ServerSideHistorySize    = CadenceMetricsPrefix + "server-side-history-size"
 	ConcurrentTaskQuota      = CadenceMetricsPrefix + "concurrent-task-quota"
 	PollerRequestBufferUsage = CadenceMetricsPrefix + "poller-request-buffer-usage"
+
+	// Concurrency Auto Scaler
+	ConcurrencyAutoScalerScope = CadenceMetricsPrefix + "concurrency-auto-scaler"
 )