pgsql: Remove less-portable-than-believed test case.

Remove less-portable-than-believed test case.

In commit 331b2369c I added a test to see what jsonb_plperl would do
with a qr{} result.  Turns out the answer is Perl version dependent.
That fact doesn't bother me particularly, but coping with multiple
result possibilities is way more work than this test seems worth.
So remove it again.

Discussion: https://postgr.es/m/E1f3MMJ-0006bf-B0@gemulon.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/eac93e20afe434a79e81558c17a7a1408cf9d74a

Modified Files
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contrib/jsonb_plperl/expected/jsonb_plperl.out  | 13 +------------
contrib/jsonb_plperl/expected/jsonb_plperlu.out | 13 +------------
contrib/jsonb_plperl/sql/jsonb_plperl.sql       | 12 ------------
contrib/jsonb_plperl/sql/jsonb_plperlu.sql      | 12 ------------
4 files changed, 2 insertions(+), 48 deletions(-)