Remove less-portable-than-believed test case.

In commit 331b2369 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

contrib/jsonb_plperl/expected/jsonb_plperl.out

@@ -39,17 +39,6 @@ SELECT testSVToJsonb();
  1
 (1 row)
 
--- unsupported (for now)
-CREATE FUNCTION testRegexpToJsonb() RETURNS jsonb
-LANGUAGE plperl
-TRANSFORM FOR TYPE jsonb
-AS $$
-my $a = qr/foo/;
-return ($a);
-$$;
-SELECT testRegexpToJsonb();
-ERROR:  cannot transform this Perl type to jsonb
-CONTEXT:  PL/Perl function "testregexptojsonb"
 -- this revealed a bug in the original implementation
 CREATE FUNCTION testRegexpResultToJsonb() RETURNS jsonb
 LANGUAGE plperl
@@ -218,4 +207,4 @@ SELECT roundtrip('{"1": {"2": [3, 4, 5]}, "2": 3}');
 
 \set VERBOSITY terse \\ -- suppress cascade details
 DROP EXTENSION plperl CASCADE;
-NOTICE:  drop cascades to 7 other objects
+NOTICE:  drop cascades to 6 other objects

contrib/jsonb_plperl/expected/jsonb_plperlu.out

@@ -39,17 +39,6 @@ SELECT testSVToJsonb();
  1
 (1 row)
 
--- unsupported (for now)
-CREATE FUNCTION testRegexpToJsonb() RETURNS jsonb
-LANGUAGE plperlu
-TRANSFORM FOR TYPE jsonb
-AS $$
-my $a = qr/foo/;
-return ($a);
-$$;
-SELECT testRegexpToJsonb();
-ERROR:  cannot transform this Perl type to jsonb
-CONTEXT:  PL/Perl function "testregexptojsonb"
 -- this revealed a bug in the original implementation
 CREATE FUNCTION testRegexpResultToJsonb() RETURNS jsonb
 LANGUAGE plperlu
@@ -218,4 +207,4 @@ SELECT roundtrip('{"1": {"2": [3, 4, 5]}, "2": 3}');
 
 \set VERBOSITY terse \\ -- suppress cascade details
 DROP EXTENSION plperlu CASCADE;
-NOTICE:  drop cascades to 7 other objects
+NOTICE:  drop cascades to 6 other objects

contrib/jsonb_plperl/sql/jsonb_plperl.sql

@@ -34,18 +34,6 @@ $$;
 SELECT testSVToJsonb();
 
 
--- unsupported (for now)
-CREATE FUNCTION testRegexpToJsonb() RETURNS jsonb
-LANGUAGE plperl
-TRANSFORM FOR TYPE jsonb
-AS $$
-my $a = qr/foo/;
-return ($a);
-$$;
-
-SELECT testRegexpToJsonb();
-
-
 -- this revealed a bug in the original implementation
 CREATE FUNCTION testRegexpResultToJsonb() RETURNS jsonb
 LANGUAGE plperl

contrib/jsonb_plperl/sql/jsonb_plperlu.sql

@@ -34,18 +34,6 @@ $$;
 SELECT testSVToJsonb();
 
 
--- unsupported (for now)
-CREATE FUNCTION testRegexpToJsonb() RETURNS jsonb
-LANGUAGE plperlu
-TRANSFORM FOR TYPE jsonb
-AS $$
-my $a = qr/foo/;
-return ($a);
-$$;
-
-SELECT testRegexpToJsonb();
-
-
 -- this revealed a bug in the original implementation
 CREATE FUNCTION testRegexpResultToJsonb() RETURNS jsonb
 LANGUAGE plperlu