JJB can take longer than 5 minutes to run

Double the timeout on the jenkins_jobs_update exec (from 5m to 10m)
because jenkins-jobs can take longer than 5 minutes to run when a
reasonably large number of jobs are defined.

Change-Id: Iff74a322a2f2e605c3c9e78f36cd8d12571e944a
Merge "JJB can take longer than 5 minutes to run"