Part of https://github.com/elastic/kibana/issues/153483

We have identified a problem with the index template/ILM policy structure so we need to stop the ILM policy from rolling over while we get a long term fix.

In investigating this I also noticed that the index templates do not set `hidden` to be true which they should.


x-pack/plugin/fleet/src/javaRestTest/java/org/elasticsearch/xpack/fleet/FleetSystemIndicesIT.java
+ indexName
            + "] starts with a dot '.', in the next major version, "
            + "index names starting with a dot are reserved for hidden indices and system indices";
        List<String> expectedWarnings = List.of(warningMsg);
        logger.info("expecting warnings: " + expectedWarnings.toString());
        RequestOptions consumeSystemIndicesWarningsOptions = RequestOptions.DEFAULT.toBuilder()
            .setWarningsHandler(warnings -> expectedWarnings.equals(warnings) == false)
            .build();
        request.setOptions(consumeSystemIndicesWarningsOptions);
    }
    public void testSearchWithoutIndexCreatedIsAllowed() throws Exception {
        Request request = new Request("GET", ".fleet-agents/_search");
        request.setJsonEntity("{ \"query\": { \"match_all\": {} } }");
        request.addParameter("ignore_unavailable", Boolean.TRUE.toString());
        assertEquals(200, client().performRequest(request).getStatusLine().getStatusCode());
    }
    public void testCreationOfFleetAgents() throws Exception {
        Request request = new Request("PUT", ".fleet-agents");
        Response response = client().performRequest(request);
        assertEquals(200, response.getStatusLine().getStatusCode());
        request = new Request("GET", ".fleet-agents/_mapping");
        response = client().performRequest(request);
        String responseBody = EntityUtils.toString(response.getEntity());
        assertThat(responseBody, containsString("access_api_key_id"));
        request = new Request("GET", ".fleet-agents-7/_mapping");
        response = client().performRequest(request);
        responseBody = EntityUtils.toString(response.getEntity());
        assertThat(responseBody, containsString("access_api_key_id"));
    }
    public void testCreationOfFleetActions() throws Exception {