Update AWS SDK Go dependency in amazon-vpc-cni-k8s to SDK V2

[orsenthil]

Current version of Amazon VPC CNI plugin (below 1.19.0) relies on the AWS SDK for Go v1 (SDK v1) to interact with AWS services. However, SDK v1 will enter maintenance mode and reach end-of-support on July 31, 2025.
This requires us to migrate AWS VPC CNI plugin to AWS SDK V2. The AWS SDK for Go v2 (SDK v2) is a complete redesign of the Go SDK code, incorporating idiomatic Go practices and increased modularity in AWS service dependencies.

Migrating to SDK v2 (https://aws.github.io/aws-sdk-go-v2/docs/migrating/) requires significant refactoring due to architectural changes.Since the types between SDK v1 and v2 are different, this means that the entire codebase must be migrated to SDK v2 in a single step.

A full migration of the entire codebase in a single shot can present challenges in terms of testing, code review, and the potential introduction of regressions.To mitigate these potential pitfalls, the approach to migration will be as follows:

1. Migrate against an upstream branch sdkv2 (https://github.com/aws/amazon-vpc-cni-k8s/tree/sdkv2). This branch will be merged into the master branch after review and testing.
2. Migrate independent clients in small pull requests against the SDK v2 branch.
3. Implement the SDK v2 configuration logic, then update the client call code paths.
4. Ensure that unit tests and integration tests are successful with every pull request.

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