Rename function name to avoid confusion

Remaning 'test_show_back_end_capabilities' to
'test_show_limits' to make its functionality clear

Change-Id: I2f2dbb7240d1473bf7def4ca6955aaeb57b7fe83
diff --git a/patrole_tempest_plugin/tests/api/volume/test_limits_rbac.py b/patrole_tempest_plugin/tests/api/volume/test_limits_rbac.py
index b49062a..fa92cad 100644
--- a/patrole_tempest_plugin/tests/api/volume/test_limits_rbac.py
+++ b/patrole_tempest_plugin/tests/api/volume/test_limits_rbac.py
@@ -25,6 +25,6 @@
     @decorators.idempotent_id('dab04510-5b86-4479-a633-6e496ff405af')
     @rbac_rule_validation.action(service="cinder",
                                  rule="limits_extension:used_limits")
-    def test_show_back_end_capabilities(self):
+    def test_show_limits(self):
         self.rbac_utils.switch_role(self, toggle_rbac_role=True)
         self.volume_limits_client.show_limits()