Makefile: aws-iam-authenticator 0.6.8

[jpmcb]

Issue number:

N/a - related to GitHub rate limiting on go mod vendor-ing all the code within this image.

Description of changes:

Makefile: aws-iam-authenticator 0.6.8

- Skip vendoring kubernetes code explicitly

This patch is twofold:

• Adds the new aws-iam-authenticator in the bottlerocket-lookaside-cache
  (which mitigates issues building the older one with direct as the goproxy
  setting - see: [Bug]: Cannot build v0.6.2 using GOPROXY direct kubernetes-sigs/aws-iam-authenticator#586)
• Skips vendoring code from kubernetes/kubernetes: the upstream project
  already vends it's dependencies, so all we need to do is pass the vendor
  directory to the license checker. My theory on the rate limiting is that since
  the docker container is using https to pull code through git, we are
  getting rate limited quickly. But since the majority of that code is in
  kubernetes, we can skip this and avoid getting rate limited

Testing done:

Able to make tools without flakes.

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[ecpullen]

Blocking until a full test has been done to ensure none of our agents are broken.
#390

[jpmcb]

The other alternative is to add a flip on GOPROXY to also use the upstream proxy and not just direct

[jpmcb]

Superseded by #810