Remove Keybase integration (#17045)

spec/fabricators/account_identity_proof_fabricator.rb

@@ -1,8 +0,0 @@
-Fabricator(:account_identity_proof) do
-  account
-  provider 'keybase'
-  provider_username { sequence(:provider_username) { |i| "#{Faker::Lorem.characters(number: 15)}" } }
-  token { sequence(:token) { |i| "#{i}#{Faker::Crypto.sha1()*2}"[0..65] } }
-  verified false
-  live false
-end