pgsql: Add regression tests for constraint errors in partitioned tables

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-

Branch
------
REL_12_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/7c836420026125f430e5ae3a3eb0264e75ec5b3e

Modified Files
--------------
src/test/regress/expected/inherit.out | 123 ++++++++++++++++++++++++++++++++++
src/test/regress/sql/inherit.sql      | 103 ++++++++++++++++++++++++++++
2 files changed, 226 insertions(+)