remove edge tests

[jenshu]

Remove kubernetes e2e tests related to:

• edge api
• glooctl
• validation webhook

Note: there may still be some references to the deleted tests/code; that should be ok since the tests don't get compiled right now. Any dangling references can be removed in follow-ups when we re-enable tests

Details

Features (i.e. folders under test/kubernetes/e2e/features) that were completely removed, because they only contained edge tests:

• basicrouting
• glooctl
• gloomtls
• validation

Features whose folders still remain, but with some/all of the edge-specific tests removed (these may be further pruned later):

• client_tls
• crd_categories
• headless_svc
• helm
• istio
• port_routing
• server_tls
• tracing
• watch_namespace_selector

Any features not mentioned above, were not touched in this PR