Fix Flight LargeList schema encoding

[yinli-systems]

Which issue does this PR close?

• Closes Schema for LargeList in Flight data encoder #10291.

Rationale for this change

prepare_field_for_flight currently rebuilds DataType::LargeList fields with Field::new_list, which changes the schema to a regular List. This silently loses the original large-list offset type in the Flight encoder's prepared schema.

The existing ListView / LargeListView path below this code already preserves the large variant, so this appears to be the same preservation rule missing for LargeList.

What changes are included in this PR?

• Use Field::new_large_list when preparing DataType::LargeList fields for Flight.
• Add a regression test that verifies the prepared Flight schema preserves a LargeList field, including field metadata and the nested item field.

Are these changes tested?

Yes, locally with Rust 1.96.0 on macOS because the repository-pinned Rust 1.96.1 toolchain download was not completing cleanly in this environment.

• RUSTUP_TOOLCHAIN=1.96.0-aarch64-apple-darwin cargo fmt --check
• RUSTUP_TOOLCHAIN=1.96.0-aarch64-apple-darwin cargo test -p arrow-flight test_large_list_schema_encoded
• RUSTUP_TOOLCHAIN=1.96.0-aarch64-apple-darwin cargo test -p arrow-flight encode::tests
• git diff --check

I used AI assistance to help inspect the nearby Flight schema-preparation paths and generate the focused regression test, then validated the change with the commands above.

Are there any user-facing changes?

Yes. Flight-encoded schemas now preserve LargeList instead of exposing it as List after schema preparation.