`aws-custom-route-controller` gets enabled on Shoot creation and gets removed in the subsequent Shoot reconciliation

[ialidzhikov]

How to categorize this issue?

/area control-plane
/kind bug
/platform aws
/priority 1

What happened:
On Shoot creation the ControlPlane gets mutated with:

    providerConfig:
      apiVersion: aws.provider.extensions.gardener.cloud/v1alpha1
      cloudControllerManager:
        useCustomRouteController: true

On a subsequent Shoot reconciliation, the gardenlet sets again the providerConfig field and the ControlPlane is reverted to:

    providerConfig:
      apiVersion: aws.provider.extensions.gardener.cloud/v1alpha1
      kind: ControlPlaneConfig

and the aws-custom-route-controller gets disabled again.

The issue is also described in gardener/gardener#6703 (comment).

What you expected to happen:
Not the above one.

How to reproduce it (as minimally and precisely as possible):
See above.

Anything else we need to know?:

Environment:

• Gardener version (if relevant): v1.38.1
• Extension version:
• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• Others: