Set default log_sanity_results to false

Author: ekouts

reframe/schemas/config.json

@@ -648,6 +648,7 @@
         "logging/handlers_perflog/httpjson_extra_headers": {},
         "logging/handlers_perflog/httpjson_debug": false,
         "logging/handlers_perflog/httpjson_backoff_intervals": [0.1, 0.2, 0.4, 0.8, 1.6, 3.2],
+        "logging/handlers_perflog/httpjson_log_sanity_results": false,
         "logging/handlers_perflog/httpjson_retry_timeout": 0,
         "modes/options": [],
         "modes/target_systems": ["*"],