Revert "cf login: complain when we encounter extraneous arguments"

This reverts commit 3b52431.

[#167948703](https://www.pivotaltracker.com/story/show/167948703)

Co-authored-by: Brendan Smith <brsmith@pivotal.io>

integration/shared/isolated/login_command_test.go

@@ -66,19 +66,10 @@ var _ = Describe("login command", func() {
 	Describe("Invalid Command Usage", func() {
 		When("a random flag is passed in", func() {
 			It("should exit 1 and display an unknown flag error message", func() {
-				session := helpers.CF("login", "--i-am-an-unknown-flag")
+				session := helpers.CF("login", "--test")
 				Eventually(session).Should(Exit(1))
 
-				Expect(session.Err).Should(Say("Incorrect Usage: unknown flag `i-am-an-unknown-flag'"))
-			})
-		})
-
-		When("an extra argument is passed in", func() {
-			It("should exit 1 and display an unexpected argument error message", func() {
-				session := helpers.CF("login",  "-a", "api.missing-fish.lite.cli.fun", "--skip-ssl-validation", "i-am-an-extra-argument")
-				Eventually(session).Should(Exit(1))
-
-				Expect(session.Err).Should(Say(`Incorrect Usage: unexpected argument "i-am-an-extra-argument"`))
+				Expect(session.Err).Should(Say("Incorrect Usage: unknown flag `test'"))
 			})
 		})
 	})

prevent_extra_args_v6.go

@@ -2,16 +2,6 @@
 
 package main
 
-import (
-	"code.cloudfoundry.org/cli/command/translatableerror"
-	"strings"
-)
-
 func preventExtraArgs(args []string) error {
-	if len(args) > 0 {
-		return translatableerror.TooManyArgumentsError{
-			ExtraArgument: strings.Join(args, " "),
-		}
-	}
 	return nil
 }