pgsql: Improve error message with JSON_SERIALIZE()

Improve error message with JSON_SERIALIZE()

The error message introduced in 3c633f3 can share the same format string
with an existing message used for JSON(), reducing the translation
effort.

Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20220708.154135.2123613118233840495.horikyota.ntt@gmail.com
Backpatch-through: 15

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0a6be1f0ec3cc9b98453bdab2d4edcfd5a00c7fa

Modified Files
--------------
src/backend/parser/parse_expr.c       | 5 +++--
src/test/regress/expected/sqljson.out | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)