Use Tempest-lib's compute security_group_default_rule

Compute security_group_default_rule has been migrated to
tempest-lib- I8b652aeb82d2a7335212ef7cc021a969ad297c6a

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 commit makes Tempest to use compute security_group_default_rule
from Tempest-lib.

Change-Id: I6be919a2845a08426758d19890919e6d97d2161d
4 files changed