modernizes for loop in cmd/, internal/ (#21309)

internal/grid/muxserver.go

@@ -130,7 +130,7 @@ func newMuxStream(ctx context.Context, msg message, c *Connection, handler Strea
 	// Fill outbound block.
 	// Each token represents a message that can be sent to the client without blocking.
 	// The client will refill the tokens as they confirm delivery of the messages.
-	for i := 0; i < outboundCap; i++ {
+	for range outboundCap {
 		m.outBlock <- struct{}{}
 	}