Add new scan metrics to flaky list in MetricsIT (#4601)

- METRICS_SCAN_RESERVATION_WRITEOUT_TIMER
- METRICS_SCAN_RESERVATION_CONFLICT_COUNTER

test/src/main/java/org/apache/accumulo/test/metrics/MetricsIT.java

@@ -104,6 +104,7 @@ public void confirmMetricsPublished() throws Exception {
     // add sserver as flaky until scan server included in mini tests.
     Set<String> flakyMetrics = Set.of(METRICS_GC_WAL_ERRORS, METRICS_FATE_TYPE_IN_PROGRESS,
         METRICS_SCAN_BUSY_TIMEOUT_COUNTER, METRICS_SCAN_RESERVATION_TOTAL_TIMER,
+        METRICS_SCAN_RESERVATION_WRITEOUT_TIMER, METRICS_SCAN_RESERVATION_CONFLICT_COUNTER,
         METRICS_SCAN_TABLET_METADATA_CACHE);
 
     Map<String,String> expectedMetricNames = this.getMetricFields();