Revert "Remove default service provider from conf file"
Revert "Remove default service provider from conf file"

Now that https://review.openstack.org/#/c/213750/ has merged,
which addresses the root issue, this symptom fixer, which has
quite a few side effects, can be reverted until it's addressed
sanely.

This reverts commit f9d5c0505752b5720beab589f9d76573740a695e.

Change-Id: Ie013b452457b460de798c5d5d06133784d2f321f

openstack/neutron-vpnaas,openstack/neutron-vpnaas