Run apparmor-tumbler test script from the source tree

Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D3480

apparmor/apparmor-tumbler.yaml

@@ -20,7 +20,7 @@ install:
 run:
   steps:
   - echo -n | sudo tee /var/log/audit/audit.log
-  - common/run-test-in-systemd --name run-test-tumbler --timeout 900 /usr/lib/apertis-tests/apparmor/tumbler/test-tumbler
+  - common/run-test-in-systemd --name run-test-tumbler --timeout 900 apparmor/tumbler/test-tumbler
   - sudo cat /var/log/audit/audit.log | aa_log_extract_tokens.pl PERMITTING REJECTING
 
 parse: