BUG-1206 Droptest: unify packet handling

Rework the two implementation to make sure they do equivalent
processing, such that the difference between the two really is only the
way they propage changes through the system.

(cherry picked from commit cbcd4ccb4f218c69d597329412a878f0e0ad3e59)
Signed-off-by: Robert Varga <robert.varga@pantheon.sk>
Signed-off-by: Michal Rehak <mirehak@cisco.com>
Change-Id: I56430b99d052be5b2623f1d3015d462ad3429b95