Update test output of sepgsql for ALTER TABLE COLUMN DROP

Update test output of sepgsql for ALTER TABLE COLUMN DROP

1df5875 has changed the way dependencies are dropped for this command
with inheritance trees, which impacts sepgsql.  This just updates the
regression test output to take care of the failures and adapt to the new
code.

Reported by buildfarm member rhinoceros.

Author: Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20191013101331.GC1434@paquier.xyz
Backpatch-through: 12