sanity-check-manual: Update expected output to include systemctl call

Commit infrastructure/apertis-test@a699e7d "Check for failed systemd units"
introduced a new call to `systemctl` that gets included even in case the test
is successful.

Update the expected output to avoid any confusion.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

test-cases/sanity-check-manual.yaml

@@ -46,7 +46,9 @@ metadata:
         + grep -E ^ID=("?)apertis\1$ /etc/os-release
         ID=apertis
         + id -u user
-        + test -S /run/user/1000/wayland-0
+        + [ -S /run/user/1000/wayland-0 ]
+        + systemctl list-units --failed --no-legend --no-pager --plain
+        + [ -n  ]
         + set +x
         # Sanity check successful