test(clob): extend order visibility polling

[cesarenaldi]

Summary

• extend metered CLOB order visibility polling from ~2s to ~8s
• keeps the existing open-orders read-path assertion while allowing for transient CLOB read latency

Verification

• POLYMARKET_RUN_METERED_TESTS=1 uv run pytest tests/integration/test_clob_orders.py -q
• uv run ruff check tests/integration/test_clob_orders.py
• uv run pyright tests/integration/test_clob_orders.py

---

Note

Low Risk
Test-only default timing change with no production or API behavior impact.

Overview
Relaxes open-order visibility polling in metered CLOB integration tests by changing _wait_for_order_visible defaults from 8 × 0.25s (~2s) to 16 × 0.5s (~8s).

The helper still polls list_open_orders until the placed order appears; only the timeout window grows so flaky failures from transient CLOB read latency are less likely. Not-visible and empty open orders helpers are unchanged.

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