Fix Mux Connect Error (#18567)

`OpMuxConnectError` was not handled correctly.

Remove local checks for single request handlers so they can 
run before being registered locally.

Bonus: Only log IAM bootstrap on startup.

internal/grid/handlers.go

@@ -89,7 +89,7 @@ var handlerPrefixes = [handlerLast]string{
 }
 
 const (
-	lockPrefix    = "lock"
+	lockPrefix    = "lockR"
 	storagePrefix = "storageR"
 )