fix(kuma-cp) add extra check under the second lock

Signed-off-by: Ilya Lobkov <lobkovilya@yandex.ru>

pkg/xds/server/callbacks/dataplane_callbacks.go

@@ -98,6 +98,14 @@ func (d *xdsCallbacks) OnStreamRequest(streamID core_xds.StreamID, request util_
 	}
 
 	d.Lock()
+	// in case client will open 2 concurrent request for the same streamID then
+	// we don't to increment the counter twice, so checking once again that stream
+	// wasn't processed
+	alreadyProcessed = d.dpStreams[streamID].dp != nil
+	if alreadyProcessed {
+		return nil
+	}
+
 	dpStream := d.dpStreams[streamID]
 	dpStream.dp = &dpKey
 	d.dpStreams[streamID] = dpStream