_mvt endpoint does not include cross cluster prefix with `_index` value. For example, `_index` returns `myIndexPattern` instead of expected `cluster_one:myIndexPattern`. _search endpoint includes cross cluster prefix with `_index` value. This is causing problems in [Kibana maps tooltips](https://github.com/elastic/kibana/issues/153210)
x-pack/plugin/vector-tile/qa/multi-cluster/src/javaRestTest/java/org/elasticsearch/vectortile/VectorTileCCSIT.java
final int numGeometries = randomIntBetween(1, 10);
        for (int i = 0; i < numGeometries; i++) {
            response = client.performRequest(putRequest);
            assertThat(response.getStatusLine().getStatusCode(), Matchers.equalTo(HttpStatus.SC_CREATED));
        }
        final Request flushRequest = new Request(HttpPost.METHOD_NAME, indexName + "/_refresh");
        response = client.performRequest(flushRequest);
        assertThat(response.getStatusLine().getStatusCode(), Matchers.equalTo(HttpStatus.SC_OK));
        return numGeometries;
    }
    public void testBasic() throws IOException {
        try (RestClient local = buildLocalClusterClient(); RestClient remote = buildRemoteClusterClient()) {
            final int localGeometries = createIndex(local, "test");
            final int remoteGeometries = createIndex(remote, "test");
            
            final Request mvtRequest = new Request(HttpPost.METHOD_NAME, "test/_mvt/location/0/0/0");
            final VectorTile.Tile localTile = execute(local, mvtRequest);
            assertThat(getLayer(localTile, "hits").getFeaturesCount(), Matchers.equalTo(localGeometries));
            final VectorTile.Tile remoteTile = execute(remote, mvtRequest);
            assertThat(getLayer(remoteTile, "hits").getFeaturesCount(), Matchers.equalTo(remoteGeometries));
            
            final Request mvtCCSRequest = new Request(HttpPost.METHOD_NAME, "/test,other:test/_mvt/location/0/0/0");
            final VectorTile.Tile ccsTile = execute(local, mvtCCSRequest);
            assertThat(getLayer(ccsTile, "hits").getFeaturesCount(), Matchers.equalTo(localGeometries + remoteGeometries));
        }
    }
    private VectorTile.Tile.Layer getLayer(VectorTile.Tile tile, String layerName) {
        for (int i = 0; i < tile.getLayersCount(); i++) {
            final VectorTile.Tile.Layer layer = tile.getLayers(i);