remove RPC_RETRIES key

Author: TanUkkii007

src/Scanner.java

@@ -1809,7 +1809,6 @@ public static class ScanMetrics extends ServerSideScanMetrics {
     public static final String NOT_SERVING_REGION_EXCEPTION_METRIC_NAME = "NOT_SERVING_REGION_EXCEPTION";
     public static final String BYTES_IN_RESULTS_METRIC_NAME = "BYTES_IN_RESULTS";
     public static final String REGIONS_SCANNED_METRIC_NAME = "REGIONS_SCANNED";
-    public static final String RPC_RETRIES_METRIC_NAME = "RPC_RETRIES";
 
     private long count_of_rpc_calls = 0;