refactor: switch BooleanBufferBuilder to NullBufferBuilder in a unit … #170

Job	Run time
cargo test hash collisions (amd64)	22m 7s
linux build test	4m 42s
Run sqllogictests with the sqlite test suite	1h 5m 4s
cargo test 'extended_tests' (amd64)	17m 40s
	1h 49m 33s

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