CH-1120: Use Drupal's element-hidden class to hide the variation edit icon

Currently, the icon is hidden with jquery's toggle(). This is problematic in that it adds inline style ```display: inline;``` and overrides the css.
I will reverse the logic. The display is a non-issue as ```.element-hidden``` is using ```!important``` and overrides ```.acquia-lift-page-variation-toggle``` since it does not use it.