Move timer tests to commitConfigUpdate

These can't use simple_layout because they need to make changes
before loading the timer configuration, so use the new
commitConfigUpdate method to swap in their configuration.  Update
it to ensure that all necessary playbooks are created.

Change-Id: I3ad25d6db2030c2aae884700115b095e8f481f2c
diff --git a/tests/base.py b/tests/base.py
index c161b15..c1e7349 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -2069,12 +2069,18 @@
         """
 
         source_path = os.path.join(FIXTURE_DIR, source_name)
-        commit_data = {}
-        with open(source_path, 'r') as nt:
-            commit_data['zuul.yaml'] = nt.read()
+        files = {}
+        with open(source_path, 'r') as f:
+            data = f.read()
+            layout = yaml.safe_load(data)
+            files['zuul.yaml'] = data
+        for item in layout:
+            if 'job' in item:
+                jobname = item['job']['name']
+                files['playbooks/%s.yaml' % jobname] = ''
         before = self.addCommitToRepo(
             project_name, 'Pulling content from %s' % source_name,
-            commit_data)
+            files)
         return before
 
     def addEvent(self, connection, event):