EnvoyProxy in EnvoyGateway without type cause infra error

Repo configurations:
```yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: envoy-gateway-config
namespace: envoy-gateway-system
data:
envoy-gateway.yaml: |
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyGateway
provider:
type: Kubernetes
kubernetes:
deploy:
type: GatewayNamespace
# increase the replicas of the rate limit deployment to 2,
# this is to test the rate limit service discovery with multiple replicas.
rateLimitDeployment:
replicas: 2
gateway:
controllerName: gateway.envoyproxy.io/gatewayclass-controller
envoyProxy:
provider:
# type: Kubernetes # without this line, there will be an error in controller
kubernetes:
envoyDeployment:
container:
resources:
limits:
cpu: 200m
memory: 200Mi
requests:
cpu: 1m
memory: 1Mi
extensionApis:
enableEnvoyPatchPolicy: true
enableBackend: true
enableLua: true
enableSDSSecretRef: true
gatewayAPI:
enabled: [XListenerSet]
rateLimit:
backend:
type: Redis
redis:
url: redis.redis-system.svc.cluster.local:6379
telemetry:
traces:
sink:
type: OpenTelemetry
openTelemetry:
host: otel-collector.monitoring.svc.cluster.local
port: 4317
protocol: grpc
samplingRate:
numerator: 100

```