### Description

The health API response can become a few MBs (2-3MB if 50K indices are affected).

In less extreme situations the response can be in the 10s/100s of KB. 

It might be worthwhile looking into chunking its response (this might provide clients with a better experience too)
server/src/main/java/org/elasticsearch/health/GetHealthAction.java
package org.elasticsearch.health;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRequest;
import org.elasticsearch.action.ActionRequestValidationException;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.action.ActionType;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.transport.TransportService;
import org.elasticsearch.xcontent.ToXContent;
import org.elasticsearch.xcontent.ToXContentObject;
import org.elasticsearch.xcontent.XContentBuilder;
import java.io.IOException;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Objects;
public class GetHealthAction extends ActionType<GetHealthAction.Response> {
    public static final GetHealthAction INSTANCE = new GetHealthAction();
    public static final String NAME = "cluster:monitor/health_api";
    private GetHealthAction() {
        super(NAME, GetHealthAction.Response::new);
    }
    public static class Response extends ActionResponse implements ToXContentObject {