Add repository and installation id to events in tests

To make test cases more realistic add the repository and installation
fields to the event as github sends them in real life as well. This
modification validates https://review.opendev.org/742211.

Change-Id: Ibcdf696c63a3f162aa835bce82f9a90d9dedd5ad

tests/base.py

@@ -2101,6 +2101,12 @@ class FakeGithubPullRequest(object):
             'sender': {
                 'login': 'ghuser'
             },
+            'repository': {
+                'full_name': self.project,
+            },
+            'installation': {
+                'id': 123,
+            },
             'labels': [{'name': l} for l in self.labels]
         }
         return (name, data)