HDFS-16181. address comment

Author: wzhallright

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/JournalMetrics.java

@@ -51,7 +51,6 @@ class JournalMetrics {
   @Metric("Number of bytes served via RPC")
   MutableCounterLong bytesServedViaRpc;
 
-  @Metric
   MutableStat rpcRequestCacheMissAmount;
 
   @Metric("Number of RPC requests with zero edits returned")