Allow rollup job creation only if cluster is x-pack ready (#30963)

Otherwise we could end up with persistent tasks metadata in the cluster that some of the nodes
might not understand in case where the cluster is during rolling upgrade from the default 6.2 to the
default 6.3 distribution.

Follow-up to #30743

Author: ywelsch

x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/action/TransportPutRollupJobAction.java

@@ -42,6 +42,7 @@
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 import org.elasticsearch.xpack.core.XPackField;
+import org.elasticsearch.xpack.core.XPackPlugin;
 import org.elasticsearch.xpack.core.rollup.RollupField;
 import org.elasticsearch.xpack.core.rollup.action.PutRollupJobAction;
 import org.elasticsearch.xpack.core.rollup.job.RollupJob;
@@ -91,6 +92,8 @@ protected void masterOperation(PutRollupJobAction.Request request, ClusterState
             return;
         }
 
+        XPackPlugin.checkReadyForXPackCustomMetadata(clusterState);
+
         FieldCapabilitiesRequest fieldCapsRequest = new FieldCapabilitiesRequest()
                 .indices(request.getConfig().getIndexPattern())
                 .fields(request.getConfig().getAllFields().toArray(new String[0]));