Make test files dynamic for unit tests

Currently they are a lot of test files we maintain for our unit tests (for example https://github.com/aws/eks-anywhere/tree/main/pkg/api/v1alpha1/testdata) which makes it inconvenient to change them all based on few spec changes. Having one common file that can be modified based on the test case using similar logic for our E2E tests can make it easier to maintain.

Start by reviewing the unit-test fixtures under pkg/api/v1alpha1/testdata and the existing E2E test logic referenced in the issue. Determine how a shared file can be modified per test case, then confirm that the unit tests pass while avoiding duplicated fixture updates after spec changes.

Written by the indexing model from the issue text.