Fix run tests in systemd

After moving tests to test group, the steps were updated. However, while doing that an error was introduced and the script was not found. When using common/run-test-in-systemd the path to the script needs to be included, to allow the script to run. This fixes errors like

boot-no-crashes/common/tee-exec: 19: boot-no-crashes.sh: not found

https://phabricator.apertis.org/T8968

Signed-off-by: Walter Lozano walter.lozano@collabora.com