run_tasks.py: fix Sentry URL
run_tasks.py: fix Sentry URL

I don't know when or why it changed, but the existing URL format, which
uses '/search?q=<id>', fails; what works, by observing the web UI's URL
submission and by testing, is to omit the 'search' part of the path:
'/?q=<id>'

Signed-off-by: Dan Mick <b07550071eaa6a9296289c43bbd6c90559196431@redhat.com>

caibo2014/teuthology,dmick/teuthology,ktdreyer/teuthology,SUSE/teuthology,dreamhost/teuthology,SUSE/teuthology,ceph/teuthology,SUSE/teuthology,robbat2/teuthology,dreamhost/teuthology,ceph/teuthology,caibo2014/teuthology,robbat2/teuthology,dmick/teuthology,ktdreyer/teuthology,dmick/teuthology