Remove tempest tests entry point
Remove tempest tests entry point

This commit removes the tempest tests entry point from setup.cfg.
Tempest tests were already removed by this commit[0]. So, we don't need
to have it.

[0] https://review.opendev.org/#/c/657793/

Change-Id: If39a269b72f854a0b2b11195e2ab022762dea2a0

openstack/networking-bgpvpn,openstack/networking-bgpvpn,openstack/networking-bgpvpn