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

bffe1bd 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

Author: akorotkov

src/backend/utils/adt/jsonpath_exec.c

@@ -1837,11 +1837,11 @@ executeDateTimeMethod(JsonPathExecContext *cxt, JsonPathItem *jsp,
 		static const char *fmt_str[] =
 		{
 			"yyyy-mm-dd",
-			"HH24:MI:SS TZH:TZM",
-			"HH24:MI:SS TZH",
+			"HH24:MI:SSTZH:TZM",
+			"HH24:MI:SSTZH",
 			"HH24:MI:SS",
-			"yyyy-mm-dd HH24:MI:SS TZH:TZM",
-			"yyyy-mm-dd HH24:MI:SS TZH",
+			"yyyy-mm-dd HH24:MI:SSTZH:TZM",
+			"yyyy-mm-dd HH24:MI:SSTZH",
 			"yyyy-mm-dd HH24:MI:SS"
 		};