Remove ov::JsonConfigExtension (#14087)

Ticket: 96278

Co-authored-by: Ilya Lavrenov <ilya.lavrenov@intel.com>

.gitmodules

@@ -63,7 +63,3 @@
 	path = thirdparty/json/nlohmann_json
 	url = https://github.com/nlohmann/json.git
 	shallow = true
-[submodule "thirdparty/json/nlohmann_json_schema_validator"]
-	path = thirdparty/json/nlohmann_json_schema_validator
-	url = https://github.com/pboettch/json-schema-validator.git
-	shallow = true