chore(eks-v2): remove awsAuth (#32961)

### Reason for this change

For `eks-v2` module, it uses `API` as authentication mode which means access entries will be used to replace aws-auth ConfigMap. `awsAuth` construct is not used anymore.

### Description of changes

- `authenticationMode` is removed from L2 because the only authentication mode allowed is `API`. The value is hardcode when creating the L1 resource.
- Remove `awsAuth` and its usage in the new module

### Description of how you validated changes
unit tests

### Checklist
- [ ] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: xazhao

packages/@aws-cdk/aws-eks-v2-alpha/lib/alb-controller.ts

@@ -1,7 +1,7 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import { Construct } from 'constructs';
-import { Cluster, AuthenticationMode } from './cluster';
+import { Cluster } from './cluster';
 import { HelmChart } from './helm-chart';
 import { ServiceAccount } from './service-account';
 import * as iam from 'aws-cdk-lib/aws-iam';
@@ -359,10 +359,6 @@ export class AlbController extends Construct {
     // the controller relies on permissions deployed using these resources.
     chart.node.addDependency(serviceAccount);
     chart.node.addDependency(props.cluster.openIdConnectProvider);
-    if (props.cluster.authenticationMode != AuthenticationMode.API) {
-      // ensure the dependency only when ConfigMap is supported
-      chart.node.addDependency(props.cluster.awsAuth);
-    }
   }
 
   private rewritePolicyResources(resources: string | string[] | undefined): string | string[] | undefined {