[sfc] Remove unused floating ip methods

As tempest.scenario.manager was announced stable interface in Tempest
27.0.0[1] it can be now reused in plugins.

Removed methods:
    * _associate_floating_ip
    * _disassociate_floating_ip

Etherpad concerning this effort:
https://etherpad.opendev.org/p/tempest-scenario-manager-cleanup

[1] https://docs.openstack.org/releasenotes/tempest/v27.0.0.html#release-notes-27-0-0

Change-Id: I317ef8253c61594aefb6def55e739dd7c5040fc1
1 file changed