test(clob): avoid full-position market order cleanup

[cesarenaldi]

Summary

• Remove live position lookup from CLOB market-order integration tests
• Exercise market-order placement with a minimum-size buy
• Best-effort clean up only the accepted order's taking amount instead of selling the full reported position

Verification

• uv run ruff format --check tests/integration/test_clob_orders.py
• uv run ruff check tests/integration/test_clob_orders.py
• uv run pyright tests/integration/test_clob_orders.py
• uv run pytest tests/integration/test_clob_orders.py -m metered --collect-only -q

Live metered tests were not run locally.

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Note

Low Risk
Changes are limited to integration test behavior and reduce live-test side effects; no production trading or client logic is modified.

Overview
Metered CLOB market-order integration tests no longer call list_positions or sell an entire reported position before exercising placement.

Both async and sync tests now always place a minimum-size FAK buy, assert an AcceptedOrder, and only best-effort sell response.taking_amount when it is greater than zero (errors suppressed). The Position import and _find_owned_token_position helper are removed.

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