browser: update tests for new login functionality

Login attempts are now allowed even without a minimum password length,
so remove test for the disablement of the submit button on login page.

Author: laurelnaiad

specs/features/authentication.feature

@@ -11,7 +11,5 @@ Feature: Authentication
     When I start to log in
     And I attempt to log in with invalid credentials
     And my login attempt is denied
-    And I attempt to log in with insufficient password length
-    And I am not allowed to submit my credentials
     And I attempt to log in as a Contributor
     Then I am logged in