fix: no need to proxy if IAM not initialized (#12416)

IAM not initialized doesn't mean we can't still
read the content from the disk, we should just
allow the request to go-through if object layer
is initialized.

cmd/generic-handlers.go

@@ -166,10 +166,7 @@ func setBrowserRedirectHandler(h http.Handler) http.Handler {
 }
 
 func shouldProxy() bool {
-	if newObjectLayerFn() == nil {
-		return true
-	}
-	return !globalIAMSys.Initialized()
+	return newObjectLayerFn() == nil
 }
 
 // Fetch redirect location if urlPath satisfies certain