promote after test success

[pcfe]

addresses #126

test successfully run in my homelab

• test failure[1] → pipeline stops after stage run tests (build 36 in the image)
• all tests successful →pipeline continues and a second test VM is instantiated from the LCE given via GOLDENVM_ENV (build 37 in the image)

[1] test failure created with this simple bats test

@test "explicit fail" {
    false
}