fix: default UDWFImpl::expressions returns all expressions #34302

Job	Run time
cargo check	6m 23s
cargo test (macos)	12m 0s
build with wasm-pack	2m 34s
cargo test (macos-aarch64)	11m 30s
Check cargo fmt	46s
Verify MSRV (Min Supported Rust Version)	8m 3s
Verify Vendored Code	55s
cargo test (win64)	1h 8m 40s
cargo test datafusion-cli (amd64)	3m 52s
cargo test (amd64)	10m 50s
cargo doc	4m 8s
cargo test doc (amd64)	15m 30s
cargo examples (amd64)	13m 53s
check Cargo.toml formatting	3m 1s
clippy	5m 54s
cargo test hash collisions (amd64)	17m 22s
Run sqllogictest with Postgres runner	3m 36s
cargo test pyarrow (amd64)	2m 53s
verify benchmark results (amd64)	13m 14s
check configs.md and ***_functions.md is up-to-date	3m 3s
	3h 28m 7s

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