Fix metrics tagging in stream replication task processing (#4625)

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**What changed?**
* Fix metrics tagging in stream replication task processing

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**Why?**
Wrong tag is used

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**Is hotfix candidate?**
Yes

service/history/replication/executable_task.go

@@ -172,7 +172,7 @@ func (e *ExecutableTaskImpl) Nack(err error) {
 	}
 	e.MetricsHandler.Counter(metrics.ReplicationTasksFailed.GetMetricName()).Record(
 		1,
-		metrics.OperationTag(metrics.SyncActivityTaskScope),
+		metrics.OperationTag(e.metricsTag),
 		metrics.NamespaceTag(namespaceName),
 	)
 }