Hide I/SLM history aliases (elastic#53564)

This commit adjusts the aliases used for the ILM and SLM history indices
to be hidden aliases.

Also tweaks the configuration of the `IndexTemplateRegistry`s used by
these history system to only upgrade the template from the master node,
as documents are indexed from the master node, so the template version
should only be upgraded from the master node.

Author: gwbrown

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/slm/history/SnapshotHistoryStore.java

@@ -98,7 +98,8 @@ static void ensureHistoryIndex(Client client, ClusterState state, ActionListener
             client.admin().indices().prepareCreate(initialHistoryIndexName)
                 .setWaitForActiveShards(1)
                 .addAlias(new Alias(SLM_HISTORY_ALIAS)
-                    .writeIndex(true))
+                    .writeIndex(true)
+                    .isHidden(true))
                 .execute(new ActionListener<CreateIndexResponse>() {
                     @Override
                     public void onResponse(CreateIndexResponse response) {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/slm/history/SnapshotLifecycleTemplateRegistry.java

@@ -43,6 +43,11 @@ public class SnapshotLifecycleTemplateRegistry extends IndexTemplateRegistry {
 
     public static final String SLM_POLICY_NAME = "slm-history-ilm-policy";
 
+    @Override
+    protected boolean requiresMasterNode() {
+        return true;
+    }
+
     public static final IndexTemplateConfig TEMPLATE_SLM_HISTORY = new IndexTemplateConfig(
         SLM_TEMPLATE_NAME,
         "/slm-history.json",

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/history/ILMHistoryStore.java

@@ -187,7 +187,7 @@ static void ensureHistoryIndex(Client client, ClusterState state, ActionListener
                 .setSettings((Map<String, ?>) templateAsMap.get("settings"))
                 .addMapping("_doc", (Map<String, Object>) templateAsMap.get("mappings"))
                 .setWaitForActiveShards(1)
-                .addAlias(new Alias(ILM_HISTORY_ALIAS).writeIndex(true))
+                .addAlias(new Alias(ILM_HISTORY_ALIAS).writeIndex(true).isHidden(true))
                 .execute(new ActionListener<CreateIndexResponse>() {
                     @Override
                     public void onResponse(CreateIndexResponse response) {

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/history/ILMHistoryTemplateRegistry.java

@@ -35,6 +35,11 @@ public class ILMHistoryTemplateRegistry extends IndexTemplateRegistry {
 
     public static final String ILM_POLICY_NAME = "ilm-history-ilm-policy";
 
+    @Override
+    protected boolean requiresMasterNode() {
+        return true;
+    }
+
     public static final IndexTemplateConfig TEMPLATE_ILM_HISTORY = new IndexTemplateConfig(
         ILM_TEMPLATE_NAME,
         "/ilm-history.json",