VMware: Remove AWS dependency for VMware testing

[ecpullen]

    This seems like another thing to fix - we should strive to have VMware testing not require any AWS credentials or resources.

Originally posted by @bcressey in bottlerocket-os/bottlerocket#2594 (comment)

[etungsten]

For migration testing for vSphere variants, we rely on SSM hybrid activations to register the SSM agents running on the control containers so they show up as managed instances in AWS. This lets us dispatch update commands via SSM Run Documents.

To fully break away from that model, I think we can integrate brupop into our testing somehow but we'd still need someway to change the settings on the hosts in a programmatic way. Ideally we'd do that through the settings operator whenever that is ready.