EG loglevel error for admin and metrics module

[qicz]

Description:

What issue is being seen? Describe what should be happening instead of
the bug, for example: Envoy should not crash, the expected value isn't
returned, etc.

Repro steps:

set the EG logleve to warn with envoy-gateway-config but the admin and metrics can not assign the level.

apiVersion: v1
data:
  envoy-gateway.yaml: |-
    apiVersion: gateway.envoyproxy.io/v1alpha1
    kind: EnvoyGateway
    logging:
      level:
        default: warn
    gateway:
      controllerName: gateway.envoyproxy.io/gatewayclass-controller
    provider:
      type: Kubernetes
      kubernetes:
        overwriteControlPlaneCerts: true
kind: ConfigMap

Note: If there are privacy concerns, sanitize the data prior to
sharing.

Environment:

Include the environment like gateway version, envoy version and so on.

Logs:

Include the access logs and the Envoy logs.

2024-09-26T14:43:44.712Z        INFO    admin   admin/server.go:37      starting admin server   {"address": "127.0.0.1:19000", "enablePprof": false}
2024-09-26T14:43:44.712Z        INFO    metrics metrics/register.go:165 initialized metrics pull endpoint       {"address": "0.0.0.0:19001", "endpoint": "/metrics"}
2024-09-26T14:43:44.713Z        INFO    metrics metrics/register.go:54  starting metrics server {"address": "0.0.0.0:19001"}