Improve a code responsible for setting an address of a subject under the test

Description

GitLab QA is a click-driven testing framework. It means that we load a browser point it to some address and then we start clicking / filling forms etc.

We started from using RSpec with Capybara, and this evolved to setting an address of a subject using the following code (that sets Capybara#app_host:

Specs::Config.perform do |specs|
  specs.address = address
end

We found a workaround for that when adding Mattermost tests. We are now adding integration tests for Geo, and this approach becomes a tech debt that needs a refactoring soon.