[python] Plan natively with pypaimon-rust releases that lack Plan.stats()

[sundapeng]

Purpose

#10609 reads planning counters with rust_plan.stats(). pypaimon-rust 0.4.0, the latest release and the one the Python / Tests jobs install, has no Plan.stats(), so every native plan raises AttributeError and falls back to the Python scanner:

Native plan failed, falling back to the Python scanner: 'pypaimon_rust.datafusion.Plan' object has no attribute 'stats'

This made ContiguousWindowPlanTest.test_native_plan_retains_independent_payload_column_files fail on Python 3.10 to 3.13. #10624 moved that test to the Rust main job, but native planning with 0.4.0 still falls back. Native CI builds pypaimon-rust from main, which has stats(), so it does not see this.

This PR reads the counters only when the binding provides stats(), as _from_native_plan already does for snapshot_id. With an older binding the plan stays native and reports no native statistics, as before #10609.

It also adds Native CI / pypaimon-rust 0.4.0, which installs the released binding and runs the regular suite with native planning forced. The version is a matrix value, so later releases can be added next to it.

Tests

• native_plan_test.py adds test_bindings_without_plan_stats_still_plan_natively, which fails without the fix.
• With pypaimon-rust 0.4.0 installed and -m 'not native_plan', contiguous_window_plan_test.py fails before the fix and passes with it.
• Native CI / pypaimon-rust 0.4.0 passes and plans natively 2402 times; before the fix the same suite plans natively twice.

[JingsongLi]

Add a CI for 0.4.0

[sundapeng]

Thanks, added in 4df684f. Native CI / pypaimon-rust 0.4.0 installs the released 0.4.0 from PyPI and runs the regular suite with native planning forced; tests marked native_plan need Rust main and stay in Native CI. It passes here with 2403 native plans. Run locally on master before the fix, the same suite fails test_native_plan_retains_independent_payload_column_files and plans natively only twice, since every other plan falls back on the missing Plan.stats(). The version is a matrix value, so the next release can be added next to it.

The Python / Native CI failure here is unrelated: apache/paimon-rust#1141 made Rust retry GET requests on 429 and 503, and four snapshot tests still expect a single 503 call. It fails the same way on master; #10626 fixes the tests.

[sundapeng]

#10624 fixed the failing Python / Tests by moving test_native_plan_retains_independent_payload_column_files to the Rust main job, so CI no longer needs this. What remains is that opt-in native planning with pypaimon-rust 0.3.0 or 0.4.0 logs a warning and falls back to the Python scanner, with correct results, until a release with Plan.stats() becomes the minimum. Closing; it can be reopened if 0.4.0 compatibility is wanted.