Fix "Save as Copy" for article issue

## PR summary
This PR fix the issue #4912 reported by @brianteeman. Basically, when you open an article, change it's title (and maybe alias), then press "Save as Copy" button, the system should create a new article with the new title (and alias) which you entered.

However, at the moment, Joomla simply ignore the change you made before pressing "Save as Copy", it simply append (2) to the title (and alias) of the original article and use it as Title (and alias) of the new article. This is unexpected behavior and this PR fix it.

## How to test 

1. Open an existing article
2. Change it's title (and maybe alias)
3. Press "Save as Copy" button. Make sure the system generate new article with the entered title (and alias), instead of appending (2) to the title of the article and use it as title of the new article.