Fix the functional test related to flavor check

Relating to https://review.opendev.org/#/c/761063/

Change-Id: I6db7f5eac55f9a1556be5e4669a758d884b3cfd3

trove/tests/scenario/runners/test_runners.py

@@ -983,7 +983,7 @@ class CheckInstance(AttrCheck):
         if 'flavor' not in self.instance:
             self.fail("'flavor' not found in instance.")
         else:
-            allowed_attrs = ['id']
+            allowed_attrs = ['id', 'links']
             self.contains_allowed_attrs(
                 self.instance['flavor'], allowed_attrs,
                 msg="Flavor")