Add scenario test for trunk E2E flow

Add Scenario test "test_parent_port_connectivity_after_trunk_deleted"
to verify the E2E flow of fix proposed for Bug: #1794424
"Enable delete bound trunk for linux bridge agent"

Co-Authored-By: Allain Legacy <Allain.legacy@windriver.com>

Depends-On: https://review.openstack.org/#/c/605589/
Change-Id: Ic2e02f4b5dc8d7930e251340d8be194733b0a4f7
Related-Bug: #1794424
Story: 2003889
5 files changed