During the Zed PTG it was decided that to solve the race condition
between os-vif and Neutron when deleting trunk bridges, os-vif will be
responsible of both the creation and the deletion of the bridge (see Day
2 first topic at [1]). This change adds the code to delete trunk
bridges.
[1] https://lists.openstack.org/pipermail/openstack-discuss/2022-April/028164.html
Change-Id: I7d834a0c31c801e96002f42f86409ba274c234e6