iamauth controller failing to reconcile due to informer issue

[alam0rt]

/kind bug

What steps did you take and what happened:
[A clear and concise description of what the bug is.]

The capa client-go is failing to list v1beta1.MachineDeployments which is in turn causing the iamauth controller to error out before it can reconcile.

  - lastTransitionTime: "2024-09-06T04:09:56Z"
    message: 'getting roles for remote workers: failed to get roles from machine deployments
      failed to list machine deployments for cluster default/manager: Timeout: failed
      waiting for *v1beta1.MachineDeployment Informer to sync'
    reason: IAMAuthenticatorConfigurationFailed

The cluster in question does not use any machine deployments (its an EKS fargate cluster).

What did you expect to happen:

For the iamauth controller to get an empty list of machine deployments and continue reconciliation.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Appears to be occurring here:

cluster-api-provider-aws/pkg/cloud/services/iamauth/reconcile.go

Lines 125 to 128 in c2c96dd

	err := s.client.List(ctx, deploymentList, selectors...)
	if err != nil {
	return fmt.Errorf("failed to list machine deployments for cluster %s/%s: %w", s.scope.Namespace(), s.scope.Name(), err)
	}

Environment:

• Cluster-api-provider-aws version: v2.5.0
• Kubernetes version: (use kubectl version): v1.30.3-eks-a18cd3a
• OS (e.g. from /etc/os-release): Fargate / bottlerocket

[k8s-ci-robot]

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