Rename remove_cookie -> delete_cookie in Capybara helper for Selenium driver

spec/support/capybara_helpers.rb

@@ -38,7 +38,7 @@ module CapybaraHelpers
 
   # Simulate a browser restart by clearing the session cookie.
   def clear_browser_session
-    page.driver.remove_cookie('_gitlab_session')
+    page.driver.delete_cookie('_gitlab_session')
   end
 end