schedule:package-and-qa:notify-failure script error

Job #311359451 failed for b62ddb46:

$ export COMMIT_NOTES_URL="https://$CI_SERVER_HOST/$CI_PROJECT_PATH/commit/$CI_COMMIT_SHA#notes-list"
$ scripts/notify-slack qa-master ":skull_and_crossbones: Scheduled QA against master failed! :skull_and_crossbones: See $CI_PIPELINE_URL. For downstream pipelines, see $COMMIT_NOTES_URL" ci_failing
/bin/sh: eval: line 114: scripts/notify-slack: not found

/cc @caalberts