Description:

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

HPA will not removed after I enable and disable it in envoyproxy resource , which leading to mismatches with the gateway's replica count.

Repro steps:

Include sample requests, environment, etc. All data and inputs
required to reproduce the bug.

1. Deployment a gateway resource, with nil hpa config in envoyproxy.
2. Enable hpa in envoyproxy.
3. Delete hpa config in envoyproxy.
4. HPA resource still exists.

Environment:
EG v1.3.0