Remove use of deprecated config options for volume API selection

Tempest has moved the Volume APIs testing to v3 as default and can be run
under v2 API via catalog_type.
- https://review.opendev.org/#/q/topic:volume-default-testing-v3+(status:open+OR+status:merged)

Below config options were deprecated since Rocky and now Tempest is going
to remove those (Needed-By patch):
    * ``CONF.volume-feature-enabled.api_v2``
    * ``CONF.volume-feature-enabled.api_v3``

Change-Id: Id17081d1bcafed71b5ff704e1126dacc44874bf5
Needed-By: https://review.opendev.org/#/c/698754/
diff --git a/ironic_tempest_plugin/manager.py b/ironic_tempest_plugin/manager.py
index c3d839d..2977740 100644
--- a/ironic_tempest_plugin/manager.py
+++ b/ironic_tempest_plugin/manager.py
@@ -81,10 +81,8 @@
         cls.security_group_rules_client = (
             cls.os_primary.security_group_rules_client)
 
-        if (CONF.volume_feature_enabled.api_v2 or
-            CONF.volume_feature_enabled.api_v3):
-            cls.volumes_client = cls.os_primary.volumes_client_latest
-            cls.snapshots_client = cls.os_primary.snapshots_client_latest
+        cls.volumes_client = cls.os_primary.volumes_client_latest
+        cls.snapshots_client = cls.os_primary.snapshots_client_latest
 
     # ## Test functions library
     #