Make the default TI pool slots '1' (#8153)
Make the default TI pool slots '1' (#8153)

(cherry picked from commit 323c1d1e0e275f9e8039a0fdb8565eb866774bbe)

owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow