Update defaults metatag title for front page

Problem/Motivation

One thing I like about Metatag is how the defaults are sensible and can be kept as is for most of the websites.
The only thing I would like to change is the front page title, to only keep the site name, to avoid the strange "| [site:name]" we can see most of the time.

From a SEO point of view, front pages are for "branding", therefore having only the site name as title feels like a sensible choice.