fix(cron): use job config for cleanup instead of hardcoded "keep" (openclaw#15427) thanks @arosstale

Verified:
- pnpm install --frozen-lockfile
- pnpm build
- pnpm check
- pnpm test

Co-authored-by: arosstale <117890364+arosstale@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/cron/isolated-agent/run.ts

@@ -598,7 +598,7 @@ export async function runCronIsolatedAgentTurn(params: {
           requesterDisplayKey: announceSessionKey,
           task: taskLabel,
           timeoutMs,
-          cleanup: "keep",
+          cleanup: params.job.deleteAfterRun ? "delete" : "keep",
           roundOneReply: synthesizedText,
           waitForCompletion: false,
           startedAt: runStartedAt,