Redirecting to /, instead of /login, on the successfully logged out page (#26999) (#27065)

We're using the successfully logged out page with the SAML provider
currently, so redirecting to the /login page is problematic since they
won't be able to login using this url. Instead, we're redirecting them
to '/' so that the auth providers can figure out what to do.

x-pack/plugins/security/public/views/logged_out/components/logged_out_page.tsx

@@ -35,7 +35,7 @@ export class LoggedOutPage extends Component<Props, {}> {
             </div>
           </header>
           <div className="loggedOut__content eui-textCenter">
-            <EuiButton href={this.props.addBasePath('/login')}>
+            <EuiButton href={this.props.addBasePath('/')}>
               <FormattedMessage id="xpack.security.loggedOut.login" defaultMessage="Login" />
             </EuiButton>
           </div>