Remove Volume V1 specific test base classes

As part of mentioned BP, all volume API tests have been shared
between V1 and V2. Now BaseVolumeV1Test & BaseVolumeV1AdminTest
class can be removed from base.py.

Partially implements: blueprint cinder-v2-api-tests

Change-Id: I57916c8cb0c4bb8d7e847655f13da2b399ab7783
diff --git a/tempest/api/volume/base.py b/tempest/api/volume/base.py
index 0e3cd92..52e48f3 100644
--- a/tempest/api/volume/base.py
+++ b/tempest/api/volume/base.py
@@ -145,10 +145,6 @@
                 pass
 
 
-class BaseVolumeV1Test(BaseVolumeTest):
-    _api_version = 1
-
-
 class BaseVolumeAdminTest(BaseVolumeTest):
     """Base test case class for all Volume Admin API tests."""
     @classmethod
@@ -222,7 +218,3 @@
             except exceptions.NotFound:
                 # The qos_specs may have already been deleted which is OK.
                 pass
-
-
-class BaseVolumeV1AdminTest(BaseVolumeAdminTest):
-    _api_version = 1