removed json test for play-java-jpa since play-java implements the same test in the same way

play-java-jpa/benchmark_config

@@ -3,7 +3,6 @@
   "tests": [{
     "jpa": {
       "setup_file": "setup",
-      "json_url": "/json",
       "db_url": "/db",
       "query_url": "/db?queries=",
       "port": 9000,