Override post-timeout for tripleo-ci jobs

Before zuulv3 the timeout for collect-logs was 40min. Now we get
some post failures with collect-logs in post-run exceeding time
limit.

Change-Id: I5fe941ea4791ed48acbe98284d4f1d7bb32ac41a
Closes-Bug: #1791169

zuul.d/base.yaml

@@ -10,6 +10,7 @@
         Base abstract job for all TripleO CI zuulv3 jobs
     parent: multinode
     timeout: 10800
+    post-timeout: 2400
     vars:
       unbound_cache_min_ttl: 900
       ara_generate_html: true