Add regression tests for constraint errors in partitioned tables.
While #16293 only applied to 11 (and 10 to some degree), it seems best
to add tests to all branches with partitioning support.
Reported-By: Daniel WM
Author: Andres Freund
Bug: #16293
Discussion: https://postgr.es/m/16293-
26f5777d10143a66@postgresql.org
Backpatch: 10-