Use floating_ips_client from tempest-lib

The files below have been migrated to tempest-lib

 * floating_ips_client.py: Ic840c3697f727612dfe754948e9a5890e7f2505d

Now Tempest-lib provides those as stable interfaces. So Tempest should
start using those from lib and remove its own copy.

Change-Id: I21c33c981249d3c7897e7d164e16562730849470
2 files changed