Stop special casing KUBE_TEST_ARGS and limiting the API
group/version settings to "v1" when running the tests. This was
helpful in the past when we used to test multiple values for
KUBE_TEST_API_VERSIONS - if you were specifying KUBE_TEST_ARGS to run a
single test case, you probably didn't want to have it tested for
multiple values of KUBE_TEST_API_VERSIONS.

Now, however, KUBE_TEST_API_VERSIONS comes from
KUBE_AVAILABLE_GROUP_VERSIONS by default, which is a single list instead
of multiple, so we shouldn't need to special case KUBE_TEST_ARGS any
more. This is especially necessary because certain tests that are using
testapi break if KUBE_TEST_API_VERSIONS is just "v1".
Signed-off-by: Andy Goldstein <goldsteina@vmware.com>