Use Standard_DS2_v2 VM size for rollback tests

Author: indusridhar

src/aks-preview/azext_aks_preview/tests/latest/test_aks_commands.py

@@ -21614,6 +21614,7 @@ def test_aks_nodepool_get_rollback_versions(self, resource_group, resource_group
         create_cmd = (
             "aks create --resource-group={resource_group} --name={name} "
             "--nodepool-name {node_pool_name} -c 1 "
+            "--node-vm-size standard_d2s_v3 "
             "--ssh-key-value={ssh_key_value}"
         )
         self.cmd(
@@ -21718,6 +21719,7 @@ def test_aks_nodepool_rollback(self, resource_group, resource_group_location):
         create_cmd = (
             "aks create --resource-group={resource_group} --name={name} "
             "--nodepool-name {node_pool_name} -c 1 "
+            "--node-vm-size standard_d2s_v3 "
             "--ssh-key-value={ssh_key_value}"
         )
         self.cmd(