fix(datafusion): skip view lookup for table functions

[shyjsarah]

Purpose

Linked issue: N/A (hotfix for a regression introduced by #494)

DataFusion preloads relation names before planning. For a query such as FROM vector_search(...), it may first ask the current schema for a table named vector_search. After REST view support was added, a missing table was reinterpreted as a view, so an error from get_view could abort planning before DataFusion resolved the registered table function.

This change prevents registered table functions from being incorrectly resolved as REST catalog views.

Brief change log

• Skip REST view fallback when a missing relation name matches a registered table function.
• Keep ordinary table and REST view resolution unchanged.
• Add a regression test using the built-in vector_search table function and a generic REST catalog.

Tests

• cargo test -p paimon-datafusion --lib sql_context::tests::registered_table_function_skips_view_lookup_during_relation_preload -- --exact --nocapture
• cargo test -p paimon-datafusion --lib rest_catalog_view — 26 passed
• cargo check -p paimon-datafusion
• cargo clippy -p paimon-datafusion --lib -- -D warnings
• cargo fmt --all -- --check

The full paimon-datafusion library test run with fulltext reached 274 passing tests. Seven existing scan tests could not load their expected table fixtures in this local environment.

API and Format

No API or storage format changes.

Documentation

No documentation changes are required.

[jerry-024]

+1