[aws-load-balancer-controller] Unknown issuer kind: Issuer with enabled CertManager

**Describe the bug**
When using `enableCertManager: true` on `aws-load-balancer-controller`, the chart creates an Issuer and a Certificate. The problem is the `issuerRef` block of the `Certificate` does not have a way to add new keys, like `group` which is needed.

With the missing group, it's possible to see `The certificate request has failed to complete and will be retried: Unknown issuer kind: Issuer`, if you do not see it, ensure to delete the created secret (and if needed regenerate the certificate again)

**Steps to reproduce**
1. Install cert-manager (in another namespace)
2. Set `enableCertManager: true`
3. Do a `describe` on the `Certificate` generated, and see: `The certificate request has failed to complete and will be retried: Unknown issuer kind: Issuer`

**Expected outcome**
A valid self-signed certificate

**Environment**

* Chart name: `aws-load-balancer-controller`
* Chart version: `1.13.4`
* Kubernetes version: `v1.33.1`
* Using EKS (yes/no), if so version? Yes, `v1.33.1-eks-595af52`

Start with the aws-load-balancer-controller chart's enableCertManager setting and inspect the generated Certificate's issuerRef block. Reproduce the issue with cert-manager installed in another namespace, then verify that the generated resource accepts the required issuer reference keys and produces a valid self-signed certificate.

Written by the indexing model from the issue text.