Remove rememberMeAriaLabel prop from LoginForm.tsx

This is in reference to issue #1737 , where this aria-label was removed from `<TextInput>`

Remove this prop:

``` 
  /* THIS PROP IS DEPRECATED AND NO LONGER USED; remove in a future breaking change release
   * Aria Label for the Remember me checkbox, use this to override using the rememberMeLabel
   * */
  rememberMeAriaLabel?: string;
```