schema_registry/json: switch jsoncons to order_preserving_policy

the switch to jsoncons::json in parse_json means that the function always performed
key sorting, making the "normalize" flag redundant

jsoncons can work in insertion-order mode, to do so we switch to the
type alias jsoncons::ojson.

this is done to preserve the original order of the input
see
tests/rptest/tests/schema_registry_test.py::SchemaRegistryAutoAuthTest.test_normalize
for an example where this can be observed externally from the schema
registry api

src/v/pandaproxy/schema_registry/json.cc

@@ -298,25 +298,25 @@ struct context {
 };
 
 template<json_schema_dialect Dialect>
-const jsoncons::jsonschema::json_schema<jsoncons::json>& get_metaschema() {
+const jsoncons::jsonschema::json_schema<jsoncons::ojson>& get_metaschema() {
     static const auto meteschema_doc = [] {
         auto metaschema = [] {
             switch (Dialect) {
             case json_schema_dialect::draft4:
                 return jsoncons::jsonschema::draft4::schema_draft4<
-                  jsoncons::json>::get_schema();
+                  jsoncons::ojson>::get_schema();
             case json_schema_dialect::draft6:
                 return jsoncons::jsonschema::draft6::schema_draft6<
-                  jsoncons::json>::get_schema();
+                  jsoncons::ojson>::get_schema();
             case json_schema_dialect::draft7:
                 return jsoncons::jsonschema::draft7::schema_draft7<
-                  jsoncons::json>::get_schema();
+                  jsoncons::ojson>::get_schema();
             case json_schema_dialect::draft201909:
                 return jsoncons::jsonschema::draft201909::schema_draft201909<
-                  jsoncons::json>::get_schema();
+                  jsoncons::ojson>::get_schema();
             case json_schema_dialect::draft202012:
                 return jsoncons::jsonschema::draft202012::schema_draft202012<
-                  jsoncons::json>::get_schema();
+                  jsoncons::ojson>::get_schema();
             }
         }();
 
@@ -329,7 +329,7 @@ const jsoncons::jsonschema::json_schema<jsoncons::json>& get_metaschema() {
 }
 
 result<json_schema_dialect> validate_json_schema(
-  json_schema_dialect dialect, const jsoncons::json& schema) {
+  json_schema_dialect dialect, const jsoncons::ojson& schema) {
     // validation pre-step: get metaschema for json draft
     const auto& metaschema_doc = [=]() -> const auto& {
         using enum json_schema_dialect;
@@ -367,7 +367,7 @@ result<json_schema_dialect> validate_json_schema(
 }
 
 result<json_schema_dialect>
-try_validate_json_schema(const jsoncons::json& schema) {
+try_validate_json_schema(const jsoncons::ojson& schema) {
     using enum json_schema_dialect;
 
     // no explicit $schema: try to validate from newest to oldest draft
@@ -392,13 +392,13 @@ try_validate_json_schema(const jsoncons::json& schema) {
 
 // forward declaration
 id_to_schema_pointer collect_bundled_schema_and_fix_refs(
-  jsoncons::json& doc, json_schema_dialect dialect);
+  jsoncons::ojson& doc, json_schema_dialect dialect);
 
 result<document_context> parse_json(iobuf buf) {
     // parse string in json document, check it's a valid json
     iobuf_istream is{buf.share(0, buf.size_bytes())};
 
-    auto decoder = jsoncons::json_decoder<jsoncons::json>{};
+    auto decoder = jsoncons::json_decoder<jsoncons::ojson>{};
     auto reader = jsoncons::basic_json_reader(is.istream(), decoder);
     auto ec = std::error_code{};
     reader.read(ec);
@@ -2193,7 +2193,7 @@ void collect_bundled_schemas_and_fix_refs(
   id_to_schema_pointer& bundled_schemas,
   jsoncons::uri base_uri,
   jsoncons::jsonpointer::json_pointer this_obj_ptr,
-  jsoncons::json& this_obj,
+  jsoncons::ojson& this_obj,
   json_schema_dialect dialect) {
     // scan the json schema object for bundled schema.
     // A bundled schema is defined as a schema with `"$id" : a_base_uri`.
@@ -2309,7 +2309,7 @@ void collect_bundled_schemas_and_fix_refs(
 }
 
 id_to_schema_pointer collect_bundled_schema_and_fix_refs(
-  jsoncons::json& doc, json_schema_dialect dialect) {
+  jsoncons::ojson& doc, json_schema_dialect dialect) {
     // entry point to collect all bundled schemas
     auto bundled_schemas = id_to_schema_pointer{};
     if (doc.is_bool()) {

src/v/pandaproxy/schema_registry/test/test_json_schema.cc

@@ -115,7 +115,7 @@ static const auto error_test_cases = std::to_array({
 })",
     pps::error_info{
       pps::error_code::schema_invalid,
-      R"(Invalid json schema: '{"$schema":"http://json-schema.org/draft-06/schema#","exclusiveMinimum":false,"minimum":0,"type":"number"}'. Error: '/exclusiveMinimum: Expected number, found boolean')"}},
+      R"(Invalid json schema: '{"$schema":"http://json-schema.org/draft-06/schema#","type":"number","minimum":0,"exclusiveMinimum":false}'. Error: '/exclusiveMinimum: Expected number, found boolean')"}},
 });
 SEASTAR_THREAD_TEST_CASE(test_make_invalid_json_schema) {
     for (const auto& data : error_test_cases) {