Fix unstable regression test result.

Commit e306df7f added a test case that depends on "the" being a
stop word, which it is not in non-English locales.  Since the
point of the test is to check stopword behavior, fix by forcibly
selecting the 'english' configuration.

Per buildfarm.

src/test/regress/expected/jsonb.out

@@ -3489,7 +3489,7 @@ select to_tsvector('simple', '{"a": "aaa bbb ddd ccc", "b": ["eee fff ggg"], "c"
 (1 row)
 
 -- jsonb to tsvector with stop words
-select to_tsvector('{"a": "aaa in bbb ddd ccc", "b": ["the eee fff ggg"], "c": {"d": "hhh. iii"}}'::jsonb);
+select to_tsvector('english', '{"a": "aaa in bbb ddd ccc", "b": ["the eee fff ggg"], "c": {"d": "hhh. iii"}}'::jsonb);
                                 to_tsvector                                 
 ----------------------------------------------------------------------------
  'aaa':1 'bbb':3 'ccc':5 'ddd':4 'eee':8 'fff':9 'ggg':10 'hhh':12 'iii':13

src/test/regress/sql/jsonb.sql

@@ -886,7 +886,7 @@ select to_tsvector('{"a": "aaa bbb ddd ccc", "b": ["eee fff ggg"], "c": {"d": "h
 select to_tsvector('simple', '{"a": "aaa bbb ddd ccc", "b": ["eee fff ggg"], "c": {"d": "hhh iii"}}'::jsonb);
 
 -- jsonb to tsvector with stop words
-select to_tsvector('{"a": "aaa in bbb ddd ccc", "b": ["the eee fff ggg"], "c": {"d": "hhh. iii"}}'::jsonb);
+select to_tsvector('english', '{"a": "aaa in bbb ddd ccc", "b": ["the eee fff ggg"], "c": {"d": "hhh. iii"}}'::jsonb);
 
 -- ts_vector corner cases
 select to_tsvector('""'::jsonb);