Test:cts: fix shutdown pattern not found issue

Systemd add patch to honour the kernel's quiet cmdline argument,
so the old message will not be output.

See http://cgit.freedesktop.org/systemd/systemd/commit/?id=e683212f049ac5d3f95fb17300cfa2fd971f78f3
Merge pull request #546 from xiali/mybranch

Test:cts: fix shutdown pattern not found issue