The step_try_insert_plan_with_phase_and_state function was using raw SQL to
insert a plan with an invalid phase value to test the CHECK constraint. However,
the raw SQL was missing the root_plan_id column, which is NOT NULL in the schema.
This caused the insert to fail with a NOT NULL violation instead of the intended
CHECK constraint violation on the phase column.
This fix adds root_plan_id to the raw SQL INSERT statement, setting it to the
same value as plan_id (for a root plan). This allows the test to properly
exercise the CHECK constraint on the phase column, ensuring the test fails for
the correct reason.
ISSUES CLOSED: #9411
HAL9000