Require a base job

This makes base jobs required and allows for a per-tenant default.

Story: 2001110
Task: 4793
Change-Id: I26ffddad8358c156cfac749ce98af70f3447f671
diff --git a/tests/fixtures/layouts/repo-checkout-no-timer.yaml b/tests/fixtures/layouts/repo-checkout-no-timer.yaml
index 2b65850..ed20bb1 100644
--- a/tests/fixtures/layouts/repo-checkout-no-timer.yaml
+++ b/tests/fixtures/layouts/repo-checkout-no-timer.yaml
@@ -8,6 +8,10 @@
         - event: ref-updated
 
 - job:
+    name: base
+    parent: null
+
+- job:
     name: integration
     override-branch: stable/havana
     required-projects: