pgsql: Remove excess space from jsonpath .datetime() default format str

Remove excess space from jsonpath .datetime() default format string

bffe1bd684 has introduced jsonpath .datetime() method, but default formats
for time and timestamp contain excess space between time and timezone. This
commit removes this excess space making behavior of .datetime() method
standard-compliant.

Discussion: https://postgr.es/m/94321be0-cc96-1a81-b6df-796f437f7c66%40postgrespro.ru
Author: Nikita Glukhov
Backpatch-through: 13

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c2aa562ea5c2bf28c347503731434f08097cf1e5

Modified Files
--------------
src/backend/utils/adt/jsonpath_exec.c | 8 +--
src/test/regress/expected/jsonb_jsonpath.out | 76 ++++++++++++++--------------
src/test/regress/sql/jsonb_jsonpath.sql | 76 ++++++++++++++--------------
3 files changed, 80 insertions(+), 80 deletions(-)