Remove the migrated service client

security_group_rules_client has been already migrated into tempest-lib
with the commit I76b1d0b1c3ffb2c366c4e6d95105d9c8fde2a22b . But we have
re-integrated tempest-lib into tempest. Then the client is duplicated now.
This patch makes clients.py use the new one and removes the old one.

Change-Id: I3a2e1f255c001b8dc60d44d24c3f6f92771f8944
2 files changed