TEST-44: fix test

We were grepping for 'hello world', and in the namespace we would
match on 'hello world', and outside, on 'echo "hello world"'. When
the condition check was fixed, the test gave a false positive.

test/units/testsuite-44.sh

@@ -6,11 +6,11 @@ systemd-analyze log-level debug
 systemd-run -p LogNamespace=foobar echo "hello world"
 
 journalctl --namespace=foobar --sync
-journalctl --namespace=foobar >/tmp/hello-world
-journalctl >/tmp/no-hello-world
+journalctl -o cat --namespace=foobar >/tmp/hello-world
+journalctl -o cat >/tmp/no-hello-world
 
-grep "hello world" /tmp/hello-world
-! grep "hello world" /tmp/no-hello-world
+grep "^hello world$" /tmp/hello-world
+grep "^hello world$" /tmp/no-hello-world && { echo 'unexpected success'; exit 1; }
 
 systemd-analyze log-level info