Unexpected service selector update after update of labels for envoy pods

*Description*:
When labels defined in [EnvoyProxy resource for envoy pods](https://gateway.envoyproxy.io/docs/api/extension_types/#kubernetespodspec), they also updated in kubernetes [Service](https://kubernetes.io/docs/concepts/services-networking/service/) selector. This behavior cause downtime when any labels added or changed for envoy pods in `EnvoyProxy` resource, because selector in service updates instantly, but update of `Deployment` require time for rollout update.

*Repro steps*:
1. Add label for envoy pod in `EnvoyProxy`;
2. Notice change in `Service` selector;

*Environment*:
It's reproducible on 1.5.4, but I believe it's introduced earlier