Support all knobs used for k8s scalability tests to run CAPI on scale

What would you like to be added (User Story)?

As an operator I would like to use the same knobs as used by sig-scalability to run kubernetes on scale on top of CAPI.

Detailed Description

In the mailing list thread about kube-up/kops there was a message:

Did you maybe try also with the informing SIG-scalaibility tests? These might require extensions to kops as we require tuning a bunch of non-obvious flags of different components.

Any kind of tuning used in SIG-scalability tests may be helpful for users of CAPI to run clusters at scale as done in the SIG-scalability tests.

This issue is to check what additional tuning is used and to check if these are supported to get set via CAPI and/or make them available.

Anything else you would like to add?

One source could be the sig-scalability test-infra:

• https://github.com/kubernetes/test-infra/blob/5a9a0d4990fe2897ef83b678f63791baecdadbbc/config/jobs/kubernetes/sig-scalability/

Or asking in slack.

Label(s) to be applied

/kind feature One or more /area label. See https://github.com/kubernetes-sigs/cluster-api/labels?q=area for the list of labels.