[ticket/12851] Remove double space from Font colour button title

[PHPBB3-12851](https://tracker.phpbb.com/browse/PHPBB3-12851)

This was mentioned in #2713
I think the space may have been intentional. I do not like it tough. I think this should be "Font colour: [color=red]text[/color] or [color=#FF0000]text[/color]" for consistency.