Add validator for cluster.routing.allocation.disk boolean settings

`cluster.routing.allocation.disk.include_relocations` and
`cluster.routing.allocation.disk.reroute_interval` are both boolean
settings, so they should have the `Validator.BOOLEAN` applied.

Fixes #9309

src/main/java/org/elasticsearch/cluster/settings/ClusterDynamicSettingsModule.java

@@ -84,8 +84,8 @@ public ClusterDynamicSettingsModule() {
         clusterDynamicSettings.addDynamicSetting(ThrottlingAllocationDecider.CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES, Validator.INTEGER);
         clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK);
         clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK);
-        clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_DISK_THRESHOLD_ENABLED);
-        clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_INCLUDE_RELOCATIONS);
+        clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_DISK_THRESHOLD_ENABLED, Validator.BOOLEAN);
+        clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_INCLUDE_RELOCATIONS, Validator.BOOLEAN);
         clusterDynamicSettings.addDynamicSetting(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_REROUTE_INTERVAL, Validator.TIME_NON_NEGATIVE);
         clusterDynamicSettings.addDynamicSetting(InternalClusterInfoService.INTERNAL_CLUSTER_INFO_UPDATE_INTERVAL, Validator.TIME_NON_NEGATIVE);
         clusterDynamicSettings.addDynamicSetting(SnapshotInProgressAllocationDecider.CLUSTER_ROUTING_ALLOCATION_SNAPSHOT_RELOCATION_ENABLED);