add test for build_nulls_with_buffer. #581

Job	Run time
Check License Header	2m 15s
build with wasm-pack	2m 40s
cargo test (macos)	7m 33s
cargo test (macos-aarch64)	8m 13s
Verify Vendored Code	50s
Check cargo fmt	44s
Verify MSRV (Min Supported Rust Version)	8m 48s
cargo test (win64)	27m 31s
cargo check	7m 25s
check configs.md and ***_functions.md is up-to-date	3m 35s
cargo test hash collisions (amd64)	17m 31s
check Cargo.toml formatting	2m 55s
clippy	2m 3s
cargo doc	2m 53s
cargo test (amd64)	10m 42s
cargo test datafusion-cli (amd64)	4m 3s
cargo test doc (amd64)	17m 10s
cargo examples (amd64)	14m 2s
Run sqllogictest with Postgres runner	3m 38s
cargo test pyarrow (amd64)	3m 2s
verify benchmark results (amd64)	12m 50s
	2h 40m 23s

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