Stop installing sfc and bgpvpn tempest plugins

Stop installing sfc and bgpvpn tempest plugins

They are being integrated into neutron tempest plugin [1][2].
It will fix our gates [3].

[1] https://github.com/openstack/neutron-tempest-plugin/commit/1a987ecb4d310328cc4c2c5628dc5018dc7afc48
[2] https://github.com/openstack/neutron-tempest-plugin/commit/8dd49aac9fa27166d76755c7d62ea9f0553d8d74
[3] https://build.opnfv.org/ci/job/functest-latest-gate/199/

Change-Id: Iafcfd0cb9b33a271cf37f269d9a3a2086eb67414
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>