Account for constant equivalence properties in union, tests #3770

Job	Run time
Check cargo fmt	26s
cargo check	10m 28s
build with wasm-pack	2m 38s
cargo test (macos)	7m 40s
cargo test (macos-aarch64)	6m 56s
Verify MSRV (Min Supported Rust Version)	7m 2s
Verify Vendored Code	50s
cargo test (win64)	38m 34s
cargo test (amd64)	9m 53s
cargo test datafusion-cli (amd64)	4m 2s
cargo examples (amd64)	13m 32s
cargo doc	3m 56s
Run sqllogictest with Postgres runner	3m 26s
cargo test doc (amd64)	14m 44s
cargo test pyarrow (amd64)	2m 59s
verify benchmark results (amd64)	12m 10s
clippy	3m 27s
cargo test hash collisions (amd64)	14m 46s
check Cargo.toml formatting	3m 0s
check configs.md is up-to-date	2m 55s
	2h 43m 24s

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