telepathy-ring-automated: Stop using audit.log

Use the systemd journal to retrieve audit messages, as the minimal images no
longer ship auditd.

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

test-cases/telepathy-ring-automated.yaml

@@ -40,7 +40,7 @@ run:
     - "# Execute the following commands:"
     - echo -n | sudo tee /var/log/audit/audit.log
     - common/run-test-in-systemd --user=user sdk/telepathy-ring-automated.sh
-    - sudo cat /var/log/audit/audit.log | aa_log_extract_tokens.pl PERMITTING REJECTING
+    - sudo journalctl -b -t audit -o cat | /usr/bin/aa_log_extract_tokens.sh ALLOWED DENIED
 
 parse:
   fixupdict: