Don't preserve functional dependency when generating UNION logical plan #33646

Job	Run time
build with wasm-pack	2m 23s
Check cargo fmt	46s
cargo check	5m 58s
cargo test (macos)	10m 52s
cargo test (macos-aarch64)	11m 16s
Verify MSRV (Min Supported Rust Version)	8m 32s
Verify Vendored Code	40s
cargo test (win64)	1h 0m 12s
cargo test datafusion-cli (amd64)	4m 19s
cargo test doc (amd64)	15m 31s
cargo test (amd64)	10m 56s
cargo doc	4m 25s
cargo examples (amd64)	13m 26s
Run sqllogictest with Postgres runner	3m 40s
cargo test pyarrow (amd64)	2m 52s
verify benchmark results (amd64)	12m 24s
check Cargo.toml formatting	3m 2s
check configs.md and ***_functions.md is up-to-date	3m 1s
cargo test hash collisions (amd64)	17m 10s
clippy	5m 28s
	3h 16m 53s

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