Fix seed boolean null handling #3948

Job	Run time
changes	7s
test-dbt-versions (1.9)	1m 48s
test-dbt-versions (1.6)	1m 46s
test-dbt-versions (1.3)	1m 44s
test-dbt-versions (1.8)	1m 45s
test-dbt-versions (1.5)	1m 37s
test-dbt-versions (1.7)	1m 48s
test-dbt-versions (1.4)	1m 32s
test-dbt-versions (1.10)	1m 49s
test-vscode-e2e	-1s
test-vscode	-1s
doc-tests	42s
migration-test	1m 38s
style-and-cicd-tests (3.13)	24m 56s
style-and-cicd-tests (3.11)	20m 26s
engine-tests-docker (mssql)	1m 52s
cicd-tests-windows	9m 55s
engine-tests-docker (trino)	9m 13s
engine-tests-docker (spark)	6m 10s
engine-tests-docker (postgres)	2m 54s
style-and-cicd-tests (3.9)	24m 29s
style-and-cicd-tests (3.12)	24m 36s
engine-tests-docker (duckdb)	1m 31s
style-and-cicd-tests (3.10)	23m 32s
engine-tests-docker (mysql)	1m 49s
engine-tests-docker (starrocks)	2m 49s
engine-tests-docker (risingwave)	2m 48s
engine-tests-docker (clickhouse)	2m 49s
ui-style	-1s
ui-test	-1s
engine-tests-cloud	0s
	2h 56m 1s

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