pgsql: Remove %error-verbose directive from jsonpath parser

Remove %error-verbose directive from jsonpath parser

None of the other bison parsers contains this directive, and it gives
rise to some unfortunate and impenetrable messages, so just remove it.

Backpatch to release 12, where it was introduced.

Per gripe from Erik Rijkers

Discussion: https://postgr.es/m/ba069ce2-a98f-dc70-dc17-2ccf2a9bf7c7@xs4all.nl

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/89a39d4a4da01b13dddcbcf9bcdac2205c9b1279

Modified Files
--------------
src/backend/utils/adt/jsonpath_gram.y       | 1 -
src/test/regress/expected/jsonb_sqljson.out | 2 +-
2 files changed, 1 insertion(+), 2 deletions(-)