**Elasticsearch version** (`bin/elasticsearch --version`): 7.16 (earlier too), 8.0, 8.1

**Description of the problem including expected versus actual behavior**:
Currently, the rollover requests are not cancellable, irrespective of the underlying incoming HTTP channel being closed (eg. by a proxy). This could result in clients receiving `504` and retrying the rollovers, resulting in multiple rollover operations being processed (some products issue rollovers without specifying conditions, so this could translate in multiple subsequent rollovers being executed).

This proposes using the `RestCancellableNodeClient` infrastructure for the rollover API, such that elasticsearch can react to the incoming HTTP connection being closed by cancelling the rollover operation.

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestRolloverIndexAction.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.rest.action.admin.indices;
import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
import org.elasticsearch.action.support.ActiveShardCount;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.common.logging.DeprecationLogger;
import org.elasticsearch.core.RestApiVersion;
import org.elasticsearch.rest.BaseRestHandler;
import org.elasticsearch.rest.RestRequest;
import org.elasticsearch.rest.action.RestToXContentListener;
import java.io.IOException;
import java.util.List;
import static org.elasticsearch.rest.RestRequest.Method.POST;
public class RestRolloverIndexAction extends BaseRestHandler {
    private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(RestRolloverIndexAction.class);
    public static final String TYPES_DEPRECATION_MESSAGE = "[types removal] Using include_type_name in rollover "
        + "index requests is deprecated. The parameter will be removed in the next major version.";
    @Override
    public List<Route> routes() {