fix(datafusion): make table definitions optional for queries

[jerry-024]

Purpose

vector_search creates a PaimonTableProvider while planning a query. The provider eagerly built a CREATE TABLE definition, so tables containing VECTOR columns failed before search execution because VECTOR cannot currently be round-tripped by SHOW CREATE TABLE.

Table definitions are optional query metadata and should not prevent a table from being queried.

Brief change log

• Treat failure to build the optional table definition as non-blocking when creating a PaimonTableProvider.
• Keep explicit SHOW CREATE TABLE validation unchanged.
• Add a regression test that plans vector_search against a VECTOR<FLOAT> column.

Tests

• cargo fmt --all -- --check
• Added test_vector_search_plans_vector_column_without_show_create_support

API and Format

No API or storage format changes.

Documentation

No documentation changes are required.

[JingsongLi]

+1