[fix](regression) Stabilize variant hirachinal array output (#63610)

Stabilize the variant predefine hirachinal regression
output by serializing `v['c']` through JSON instead of relying on
variant string formatting, which can differ in insignificant array
whitespace.

Author: eldenmoon

regression-test/data/variant_p0/predefine/variant_hirachinal.out

@@ -12,7 +12,7 @@
 6	{"a":1234,"xxxx":"kaana"}
 
 -- !sql --
-[1, 2, 3]
+[1,2,3]
 {"c":456,"d":"null","e":7.111}
 
 -- !sql --

regression-test/suites/variant_p0/predefine/variant_hirachinal.groovy

@@ -33,9 +33,9 @@ suite("regression_test_variant_predefine_hirachinal", "variant_type"){
     sql """insert into  ${table_name} select * from (select -2, '{"a": 11245, "b" : [123, {"xx" : 1}], "c" : {"c" : 456, "d" : "null", "e" : 7.111}}'  as json_str
             union  all select -1, '{"a": 1123}' as json_str union all select *, '{"a" : 1234, "xxxx" : "kaana"}' as json_str from numbers("number" = "4096"))t order by 1 limit 4098 ;"""
     qt_sql "select * from ${table_name} order by k limit 10"
-    qt_sql "select cast(v['c'] as string) from ${table_name} where k = -3 or k = -2 order by k"
+    qt_sql "select cast(v['c'] as json) from ${table_name} where k = -3 or k = -2 order by k"
     qt_sql "select v['b'] from ${table_name} where k = -3 or k = -2"
     sql """insert into ${table_name} values (-3, '{"c" : 12345}')"""
-    order_qt_sql1 "select cast(v['c'] as string) from var_rs where k = -3 or k = -2 or k = -4 or (k = 1 and v['c'] = 1024) order by k"
-    order_qt_sql2 "select cast(v['c'] as string) from var_rs where k = -3 or k = -2 or k = 1 order by k, cast(v['c'] as text) limit 3"
-}
+    order_qt_sql1 "select cast(v['c'] as json) from var_rs where k = -3 or k = -2 or k = -4 or (k = 1 and v['c'] = 1024) order by k"
+    order_qt_sql2 "select cast(v['c'] as json) from var_rs where k = -3 or k = -2 or k = 1 order by k, cast(v['c'] as text) limit 3"
+}