Chunk events by day

Scanning the page is difficult at the moment because it’s hard to tell
how far apart in time events are, and thereby determine which events
might be related.

Grouping the events by day quickly lets users narrow their focus to
a meaningful subset of the events.

tests/conftest.py

@@ -3514,9 +3514,10 @@ def mock_get_service_history(mocker):
                 'created_by_id': sample_uuid(),
             },
             {
+                'name': 'Real service',
                 'created_at': '2010-10-10T10:10:10.000000Z',
                 'updated_at': '2012-12-12T12:12:12.000000Z',
-                'created_by_id': uuid4(),
+                'created_by_id': sample_uuid(),
             },
         ],
         'api_key_history': [