ES passthrough should not accept malformed JSON

A command like this one will return 200, note that the content-type header is included:

curl -u Administrator:Administrator -X GET localhost:8080/nuxeo/site/es/_all/_search -d '{"query":{"simple_query_string":{"query":"video"}}}junk' -H content-type:application/json

Likewise using a payload like "{\"query\": {\"match_all\": {}junk"}} in TestSearchRequestFilter will not result in an error.

Client has security concerns and needs this to be rectified.