Fix mux client memory leak (#18956)

Add missing client cancellation, resulting in memory buildup tracing back to context.WithCancelCause/context.WithCancelDeadlineCause

internal/grid/connection.go

@@ -287,6 +287,7 @@ func (c *Connection) newMuxClient(ctx context.Context) (*muxClient, error) {
 	if dl, ok := ctx.Deadline(); ok {
 		client.deadline = getDeadline(time.Until(dl))
 		if client.deadline == 0 {
+			client.cancelFn(context.DeadlineExceeded)
 			return nil, context.DeadlineExceeded
 		}
 	}
@@ -333,6 +334,7 @@ func (c *Connection) Request(ctx context.Context, h HandlerID, req []byte) ([]by
 			_, ok := c.outgoing.Load(client.MuxID)
 			fmt.Println(client.MuxID, c.String(), "Connection.Request: DELETING MUX. Exists:", ok)
 		}
+		client.cancelFn(context.Canceled)
 		c.outgoing.Delete(client.MuxID)
 	}()
 	return client.traceRoundtrip(ctx, c.trace, h, req)

internal/grid/stream.go

@@ -63,10 +63,11 @@ func (s *Stream) Send(b []byte) error {
 func (s *Stream) Results(next func(b []byte) error) (err error) {
 	done := false
 	defer func() {
+		if s.cancel != nil {
+			s.cancel(err)
+		}
+
 		if !done {
-			if s.cancel != nil {
-				s.cancel(err)
-			}
 			// Drain channel.
 			for range s.responses {
 			}