ceph-dashboard-pull-requests: fix permission denied error

ceph-dashboard-pull-requests: fix permission denied error

as stdout redirect is performed by the shell, and shell is launched by
the "jenkins" user, so permission denied is expected when we are trying
to create a file under /etc/yum.repos.d/. in that case, we'll have
following failure:

/tmp/jenkins8899238112048417478.sh: line 14:
/etc/yum.repos.d/google-chrome.repo: Permission denied
Build step 'Execute shell' marked build as failure

Signed-off-by: Kefu Chai <kchai@redhat.com>