Revert "Increase HTTP client timeout for predictions"

This reverts commit 9f821e4.

Author: deliahu

cli/cmd/lib_client.go

@@ -48,7 +48,7 @@ type cortexClient struct {
 
 var httpClient = &cortexClient{
 	Client: &http.Client{
-		Timeout: time.Second * 300,
+		Timeout: time.Second * 20,
 	},
 }