Remove check-uk-visa-v2 Smart Answer

[chrisroos]

This v2 was last changed on April 22nd1, shortly before being merged to the
v1 on April 24th2.

@tadast had originally suggested keeping the v2 around as we were expecting
some more changes. We're yet to receive the changes and we should be using git
branching and Heroku from now on. @tadast confirmed that it was OK to remove
this v2 in a comment on 41276f.

Before removing I compared the v1 and v2 files:

• Flow file differences

  $ diff lib/smart_answer_flows/check-uk-visa{,-v2}.rb
  < class CheckUkVisaFlow < Flow
  > class CheckUkVisaV2Flow < Flow
  < name 'check-uk-visa'
  > name 'check-uk-visa-v2'
  < status :published
  > status :draft
  < additional_countries = UkbaCountry.all
  > additional_countries = UkbaCountry.v2_all
  > outcome :outcome_visit_business_n
  > outcome :outcome_business_y
  

• Locale file differences

  $ diff lib/smart_answer_flows/locales/en/check-uk-visa{,-v2}.yml
  < check-uk-visa:
  > check-uk-visa-v2:
  

• UKBA additional countries data differences

  $ diff lib/data/ukba_additional_countries{,_v2}.yml
  # No difference