Trim metrics scope for task-ack histogram

Signed-off-by: zawadzki <zawadzki@uber.com>

Author: dianazawadzki

common/metrics/defs.go

@@ -2651,7 +2651,6 @@ const (
 	CacheRequests
 	CacheFailures
 	CacheLatency
-	ExponentialCacheLatency
 	CacheHitCounter
 	CacheMissCounter
 	CacheFullCounter
@@ -2733,7 +2732,6 @@ const (
 	ReplicationTasksReturned
 	ReplicationTasksReturnedDiff
 	ReplicationTasksAppliedLatency
-	ExponentialReplicationTasksAppliedLatency
 	ReplicationTasksBatchSize
 	ReplicationDynamicTaskBatchSizerDecision
 	ReplicationDLQFailed
@@ -3472,11 +3470,10 @@ var MetricDefs = map[ServiceIdx]map[MetricIdx]metricDefinition{
 		UnbufferReplicationTaskTimer:                                 {metricName: "unbuffer_replication_tasks", metricType: Timer},
 		HistoryConflictsCounter:                                      {metricName: "history_conflicts", metricType: Counter},
 		CompleteTaskFailedCounter:                                    {metricName: "complete_task_fail_count", metricType: Counter},
-		CacheSize:                                                    {metricName: "cache_size", metricType: Gauge},
+		CacheSize:                                                    {metricName: "cache_size", metricType: Timer},
 		CacheRequests:                                                {metricName: "cache_requests", metricType: Counter},
 		CacheFailures:                                                {metricName: "cache_errors", metricType: Counter},
 		CacheLatency:                                                 {metricName: "cache_latency", metricType: Timer},
-		ExponentialCacheLatency:                                      {metricName: "cache_latency_ns", metricType: Histogram, exponentialBuckets: Low1ms100s},
 		CacheHitCounter:                                              {metricName: "cache_hit", metricType: Counter},
 		CacheMissCounter:                                             {metricName: "cache_miss", metricType: Counter},
 		CacheFullCounter:                                             {metricName: "cache_full", metricType: Counter},
@@ -3550,7 +3547,6 @@ var MetricDefs = map[ServiceIdx]map[MetricIdx]metricDefinition{
 		ReplicationTasksReturned:                                     {metricName: "replication_tasks_returned", metricType: Timer},
 		ReplicationTasksReturnedDiff:                                 {metricName: "replication_tasks_returned_diff", metricType: Timer},
 		ReplicationTasksAppliedLatency:                               {metricName: "replication_tasks_applied_latency", metricType: Timer},
-		ExponentialReplicationTasksAppliedLatency:                    {metricName: "replication_tasks_applied_latency_ns", metricType: Histogram, exponentialBuckets: Low1ms100s},
 		ReplicationTasksBatchSize:                                    {metricName: "replication_tasks_batch_size", metricType: Gauge},
 		ReplicationDynamicTaskBatchSizerDecision:                     {metricName: "replication_dynamic_task_batch_sizer_decision", metricType: Counter},
 		ReplicationDLQFailed:                                         {metricName: "replication_dlq_enqueue_failed", metricType: Counter},