zuul: Bump base job timeout to 2.5h

The old timeout is 2h and we are recently seeing rather frequent
timeouts when the jobs are running on slow (rax) nodes where the job is
terminated quite close to possibly successfully finishing.

Change-Id: Ib7fc12415c8b415925e8af7ba41f597289dbcc66
(cherry picked from commit c2d4e12)

Author: osfrickler

zuul.d/base.yaml

@@ -4,7 +4,7 @@
     pre-run: tests/pre.yml
     run: tests/run.yml
     post-run: tests/post.yml
-    timeout: 7200
+    timeout: 9000
     post-timeout: 1800
     required-projects:
       - openstack/ansible-collection-kolla