[BUG] — E2e: 30s blind sleeps gating async MQ consumption

- severity: Low-Medium; files: `shenyu-e2e/shenyu-e2e-case/shenyu-e2e-case-logging-rocketmq/.../DividePluginCases.java:103` (`Thread.sleep(1000*30)` before starting the MQ consumer) and `:121` (sleep 30s before `assertTrue(isLog.get())`)
- description: Fixed 30s sleeps around `DefaultMQPushConsumer` async delivery. The first sleep can even cause the consumer to miss the message published before `consumer.start()`.
- impact: `DividePluginCases` e2e assertion fails on slow broker.
- suggested_fix: Start the consumer before publishing; poll `isLog` with `Awaitility` and a bounded timeout.
- confidence: High

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_Identified during the 2026-08-02 deep re-scan; full list in [`docs/scan2-2026-08-02/06-medium-tiers.md`](docs/scan2-2026-08-02/06-medium-tiers.md)._