feat(dataproxy): remove 'SetCookie' from reponse
feat(dataproxy): remove 'SetCookie' from reponse

set cookie could potentialll leak information about the
datasource if in proxy mode.

closes #3845

grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana