Simplify getting protocol agnostic hostname

[michalkleiner]

The private method isn't really needed as it's not used anywhere else in the class and a one liner can be used instead.

[Firesphere]

But what's the use of it?
Speed wise, it's barely a difference, and it's only on write on SiteConfig, so it's not anything of any performance improvement to actual visitors.
It reduces readability of the code, with only a very, very minor speed improvement...