Ensure server and backed volume are created in the same AZ

This change ensures that the server and its associated backed volume
are created in the same AZ, addressing scenarios where mismatched AZs
could lead to operational failures or inconsistencies.

Closes-Bug: #2089766

Change-Id: Ibd33dbe024d9f82cd17bb072664ae56ce0604388
diff --git a/cinder_tempest_plugin/api/volume/base.py b/cinder_tempest_plugin/api/volume/base.py
index 1c64973..e049ff3 100644
--- a/cinder_tempest_plugin/api/volume/base.py
+++ b/cinder_tempest_plugin/api/volume/base.py
@@ -91,6 +91,10 @@
             name = data_utils.rand_name(cls.__name__ + '-Volume')
             kwargs['name'] = name
 
+        if CONF.compute.compute_volume_common_az:
+            kwargs.setdefault('availability_zone',
+                              CONF.compute.compute_volume_common_az)
+
         volume = cls.volumes_client.create_volume(**kwargs)['volume']
         cls.addClassResourceCleanup(
             cls.volumes_client.wait_for_resource_deletion, volume['id'])