Fix AI.Suggestion op updating doc

https://github.com/nuxeo/nuxeo-ai/blob/master/nuxeo-ai-model/src/main/java/org/nuxeo/ai/model/serving/SuggestionOp.java#L100.
entry.getKey() does not explicitly sends the schema, so if you have 2 different schemas with that property, it can follow on the wrong schema.
 
It a document has both video and picture schemas, they will have both the property info that has different fields for each schema.