Transforms can be configured to search incredibly broad index patterns. These cause the lower level actions used by transforms to iterate huge numbers of shards unless measures are taken to restrict which shards are considered using information available in cluster state.

Anywhere where transforms calls an action that iterates shards it must use the `index_filter` functionality of that action to reduce scope. Calls to be changed:

- [x] Field caps
- [x] Creating PIT readers - requires #99740 be implemented as a pre-requisite
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.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; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */
package org.elasticsearch.xpack.transform.transforms;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ResourceNotFoundException;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.admin.indices.refresh.RefreshAction;
import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
import org.elasticsearch.action.bulk.BulkAction;
import org.elasticsearch.action.bulk.BulkItemResponse;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.search.ClosePointInTimeAction;
import org.elasticsearch.action.search.ClosePointInTimeRequest;
import org.elasticsearch.action.search.OpenPointInTimeAction;
import org.elasticsearch.action.search.OpenPointInTimeRequest;
import org.elasticsearch.action.search.SearchAction;