Refactor the ebiptablesTearNewRules function so that the teardown of temporary
filters can also be called by the ebiptablesAllTeardown function.

This fixes a problem that leaves temporary filters behind when a VM shuts down
while its filters are modified.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

v1->v2:
  - test cases adjusted to expect more commands