Don't run sanity-check twice

Both common-*boot-tpl.yaml and group-*-tpl.yaml are running the sanity-check tests due to historical reasons that date back to LAVAv1 where a reboot was needed between the two set of tests.

Nowadays running the test twice is no longer needed, so drop the sanity-check in group-*-tpl.yaml and rename sanity-check-initial to sanity-check in common-*boot-tpl.yaml.