Fixes #4744 - copied text is shrinked (editor)

[Eldenroot]

Resolves #4744

[Sama34]

https://community.mybb.com/thread-239899.html

I think the logic is conflicting, as the equivalent of 1 would be xx-small, something around the sort of :

if($size < 7)
{
    return "<span style=\"font-size: small;\" class=\"mycode_size\">{$text}</span>";
}

Overall there seems to be some mixing confusion around the code and UI.

What do you think @mybb/developers

Also, a template should be added to remove related HTML inline code. Probably better suited for 1.9