allocation: fix typo in balancing round interval setting (elastic#136342) (elastic#136346)

The AllocationBalancingRoundSummaryService has an interval setting,
balancer_round_summaries_interval, that was previously named with a typo
(balanace). This 2 character change fixes this typo.

Author: schase-es

server/src/main/java/org/elasticsearch/cluster/routing/allocation/allocator/AllocationBalancingRoundSummaryService.java

@@ -47,7 +47,7 @@ public class AllocationBalancingRoundSummaryService {
 
     /** Controls how frequently in time balancer round summaries are logged. */
     public static final Setting<TimeValue> BALANCER_ROUND_SUMMARIES_LOG_INTERVAL_SETTING = Setting.timeSetting(
-        "cluster.routing.allocation.desired_balance.balanace_round_summaries_interval",
+        "cluster.routing.allocation.desired_balance.balancer_round_summaries_interval",
         TimeValue.timeValueSeconds(10),
         TimeValue.ZERO,
         Setting.Property.NodeScope,