schedule_suite.sh: bump suite timeout from 6->8 hours
schedule_suite.sh: bump suite timeout from 6->8 hours

This captures the current slow rbd tasks.

Signed-off-by: Sage Weil <6dd34506bbd5e58221bbb3e4732d97c91f02277b@inktank.com>

ceph/teuthology,tchaikov/teuthology,caibo2014/teuthology,t-miyamae/teuthology,michaelsevilla/teuthology,zhouyuan/teuthology,SUSE/teuthology,michaelsevilla/teuthology,zhouyuan/teuthology,dmick/teuthology,yghannam/teuthology,dreamhost/teuthology,ivotron/teuthology,yghannam/teuthology,t-miyamae/teuthology,dmick/teuthology,SUSE/teuthology,robbat2/teuthology,SUSE/teuthology,ktdreyer/teuthology,caibo2014/teuthology,dmick/teuthology,dreamhost/teuthology,ivotron/teuthology,ceph/teuthology,robbat2/teuthology,tchaikov/teuthology,ktdreyer/teuthology