chore(offpolicy): remove inference request timeout config

[TATP-233]

Summary

• Remove training.inference_request_timeout_sec from all SAC, FlashSAC, and WarpSAC owner configs.
• Remove timeout-specific task overrides, tests, comments, and stale cold-start documentation.
• Update the Newton documentation to describe learner-owned warmup plus the collector-ready handshake rather than a collector tick timeout.
• Keep the change strict: no compatibility aliases or compatibility layer.

Follow-up to unilabsim/unilab_rl#50. The upstream change has not been released yet, so local validation installed unilab_rl from the sibling checkout as an editable dependency.

Testing

• uv run --no-sync pytest tests/algos/test_offpolicy_double_buffer_runner.py tests/config/test_g1_motion_tracking_owners.py -q
• UV_NO_SYNC=1 make check

Both passed. A local UV_NO_SYNC=1 make test also had 1565 passed, 27 skipped; its single failure is the pre-existing benchmark documentation contract failure on unmodified main (_num_envs, num_steps, and warmup_steps in scripts/benchmark/outputs/env_step/env_step_breakdown.md), reproduced independently before this change.