Ensure no dangling resources are left if tests are skipped

When tenant isolation is enabled, some network resources are
provisioned even though some tests are skipped. This has
a bad effect because these resources (like ip allocations,
routers and such) may have quota's default values that are
low.

With this change we ensure resources are torn down correctly.

Closes-bug:  1254166
Related-bug: 1232971
Related-bug: 1253966

Change-Id: Id86841775a26f12a5ae8c520a086e5f1ebd63135
2 files changed