AT:

• only one aggregationType value is returned in the result depending on aggregation type (e.g "avg" when specified in configuration)
• the rest api documentation is updated

Background:
Because recently we changed the sorting of the aggregationtypes to happen on the backend it is necessary for the client to send a new request when aggregation type is changed.
Therefore it is not beneficial anymore to return all the different aggregation type results in the result and it should be refactored to only return the current value instead.