cargo make test for metal-k8s variants

[webern]

Get cargo make test working for testing metal-k8s variants (probably using tinkerbell).

depends on:

• bottlerocket metal instance provider bottlerocket-test-system#415

depends on (for precedence):

• cargo make test for aws-k8s sonobuoy #2148
• cargo make test for aws-k8s upgrade-downgrade testing #2149

We might also say that it depends on this:

• support more secure secrets bottlerocket-test-system#414