Generate Zuul log manifest with index links

Tell Zuul to link to index.html files rather than bare directories
in the log viewer.

Change-Id: I546f5997176e1caedc4a544a3d3e1e3397b3ee7a

playbooks/base/post-logs.yaml

diff --git a/playbooks/base/post-logs.yaml b/playbooks/base/post-logs.yaml
index 9c41c82..60fb160 100644
--- a/playbooks/base/post-logs.yaml
+++ b/playbooks/base/post-logs.yaml
@@ -1,6 +1,7 @@
 - hosts: localhost
   roles:
-    - generate-zuul-manifest
+    - role: generate-zuul-manifest
+      generate_zuul_manifest_index_links: True
     - role: upload-logs-gcs
       zuul_log_container: gerrit_zuul_logs2
       zuul_log_credentials_file: /authdaemon/token