Use Tempest-lib's compute floating_ips_bulk_client

Compute floating_ips_bulk_client has been migrated to
tempest-lib- I52c0cfcbfd65e3143d608200b6cac07dac006ccc

Now Tempest-lib provides this client as stable interface so Tempest
should start using this from lib and remove its own copy.
Also remove its unit tests.

This commits makes Tempest to use compute floating_ips_bulk_client
from Tempest-lib.

Change-Id: I6d87f6056318b58f83a3be9feef3872ecf694af4
3 files changed