Fix issue with floating ips for test_share_basic_ops

As far as Nova extensions are deprecated we should replace
compute_floating_ips_client on floating_ips_client

Change-Id: I8484a4186609f79b8c501121a7adbffe75f15e30
Closes-Issue: https://mirantis.jira.com/browse/PROD-20608
(cherry picked from commit 58c93ef3fd9ba73c39671cef6ac3da684c424018)
1 file changed