### Description

We've been working on the health API for a while and the breaking changes have slowed to the point where we can promote the API away from the `/_internal` categorization.
server/src/main/java/org/elasticsearch/health/RestGetHealthAction.java
private static final String VERBOSE_PARAM = "verbose";
    private static final String SIZE_PARAM = "size";
    @Override
    public String getName() {
        
        return "health_action";
    }
    @Override
    public List<Route> routes() {
        return List.of(new Route(GET, "/_internal/_health"), new Route(GET, "/_internal/_health/{indicator}"));
    }
    @Override
    protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
        String indicatorName = request.param("indicator");
        boolean verbose = request.paramAsBoolean(VERBOSE_PARAM, true);
        int size = request.paramAsInt(SIZE_PARAM, 1000);
        GetHealthAction.Request getHealthRequest = new GetHealthAction.Request(indicatorName, verbose, size);
        return channel -> new RestCancellableNodeClient(client, request.getHttpChannel()).execute(
            GetHealthAction.INSTANCE,
            getHealthRequest,
            new RestChunkedToXContentListener<>(channel)
        );
    }
}