Enable write-load decider by default, remove feature flag

Author: nicktindall

server/src/main/java/org/elasticsearch/cluster/routing/allocation/WriteLoadConstraintSettings.java

@@ -15,7 +15,6 @@
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.unit.RatioValue;
-import org.elasticsearch.common.util.FeatureFlag;
 import org.elasticsearch.core.TimeValue;
 
 /**
@@ -24,7 +23,6 @@
 public class WriteLoadConstraintSettings {
 
     private static final String SETTING_PREFIX = "cluster.routing.allocation.write_load_decider.";
-    private static final FeatureFlag WRITE_LOAD_DECIDER_FEATURE_FLAG = new FeatureFlag("write_load_decider");
 
     public enum WriteLoadDeciderStatus {
         /**
@@ -61,7 +59,7 @@ public boolean disabled() {
     public static final Setting<WriteLoadDeciderStatus> WRITE_LOAD_DECIDER_ENABLED_SETTING = Setting.enumSetting(
         WriteLoadDeciderStatus.class,
         SETTING_PREFIX + "enabled",
-        WRITE_LOAD_DECIDER_FEATURE_FLAG.isEnabled() ? WriteLoadDeciderStatus.ENABLED : WriteLoadDeciderStatus.DISABLED,
+        WriteLoadDeciderStatus.ENABLED,
         Setting.Property.Dynamic,
         Setting.Property.NodeScope
     );