Avoiding hybrid query if count targets an aggregable field

It seems that a hybrid query is performed on `select count(field) ...` query, even if the target field is aggregable, projectable (new annotations) or stored (old annotations).
This could lead a bad performance.

Workaround

If the aggregation function targets non-numeric values (e.g., string values), it is possible to perform one query individually (for each group) and get the count to compute the results. Here is an example of using it:

https://github.com/fax4ever/infinispan-play/blob/59e5193e34bc0f4ea80152b195fe0404062d385b/aggregation-massive/src/test/java/fax/play/SmokeTest.java#L65