feat(dataproxy): remove 'SetCookie' from reponse

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

closes #3845

pkg/api/dataproxy.go

@@ -103,5 +103,6 @@ func ProxyDataSourceRequest(c *middleware.Context) {
 		proxy := NewReverseProxy(ds, proxyPath, targetUrl)
 		proxy.Transport = dataProxyTransport
 		proxy.ServeHTTP(c.Resp, c.Req.Request)
+		c.Resp.Header().Del("Set-Cookie")
 	}
 }