Use EDS instead of STRICT_DNS for Ratelimit Cluster in Envoy Gateway

*Description*:
Currently, the ratelimit cluster that is spawned by Envoy Gateway uses the STRICT_DNS discovery type. However, since the Envoy Gateway is responsible for spawning and managing this service internally, it has full visibility into the ratelimit service and could instead use Endpoint Discovery Service (EDS) — which is the preferred and more dynamic method of service discovery in Envoy.

Using EDS provides several advantages:

- More flexible scaling and dynamic endpoint management.
- Avoids reliance on DNS resolution, which can have caching/staleness or timeout issues.
- Aligns with how other internally-managed services are typically handled in Envoy.