Envoy and control-plane xDS over ADS protocol deadlock when filtering stats

*Description*:
When using a `stats_matcher` `inclusion_list`, Envoy using the ADS variant of the xDS protocol will fail to receive cluster updates from the [control-plane](https://github.com/envoyproxy/go-control-plane).
After receiving an initial Cluster list, Envoy will no longer receive cluster updates.
When paired with envoyproxy/go-control-plane in ADS mode, this can cause EDS updates to stall if the cluster list is later expanded.

*Repro steps*:
[A docker-compose reproduction of the issue with Envoy 1.12.2 and 1.13.0](https://github.com/dfjones/envoy-stats-filter-repro)

*Relevant Links*:
* [Background on go-control-plane's ADS consistency behavior](https://github.com/envoyproxy/go-control-plane/issues/119)