Cleanup bgpvpn envtries at the end of test

At the moment bgpvpns are removed when all tests finished in class
resource_cleanup. The patch adds addCleanup() at the places
where bgpvpn entries are created to let them cleanned after single
test finished.

Also add cleanup for some API tests that were completely missing.

Related-Prod: PRODX-12050
Change-Id: I94229f2d6cc3331a61a57e5d03231fa8640857b6
3 files changed