fix: job hook scripts pre-emptively expands shell parameters (#686)

The `job_started_script` and `job_completed_script` pre-emptively expand
any shell parameters defined in them, resulting in them being expanded
when the `/opt/runner/job_started_script.sh` and
`/opt/runner/job_completed_script.sh` files are created and not at
runtime of the job.

Instructing the heredoc document to skip expanding any shell parameters
gives the expected functionality without having to escape them in the
config file.

runner_manager/bin/startup.sh

@@ -144,11 +144,11 @@ function setup_runner {
 		sudo -H -u actions bash -c "nohup /home/actions/actions-runner/run.sh --jitconfig \"${JIT_CONFIG}\" 2>/home/actions/actions-runner/logs &"
 	fi
 
-	cat <<EOF >/opt/runner/job_started_script.sh
+	cat <<'EOF' >/opt/runner/job_started_script.sh
 ${RUNNER_JOB_STARTED_SCRIPT}
 EOF
 
-	cat <<EOF >/opt/runner/job_completed_script.sh
+	cat <<'EOF' >/opt/runner/job_completed_script.sh
 ${RUNNER_JOB_COMPLETED_SCRIPT}
 EOF