Fix EU plaid flow (#1761)

* Fix EU plaid flow

* Fix failing tests

app/models/concerns/plaidable.rb

@@ -2,22 +2,25 @@ module Plaidable
   extend ActiveSupport::Concern
 
   class_methods do
-    def plaid_provider
-      Provider::Plaid.new if Rails.application.config.plaid
+    def plaid_us_provider
+      Provider::Plaid.new(Rails.application.config.plaid, :us) if Rails.application.config.plaid
     end
 
     def plaid_eu_provider
-      Provider::Plaid.new if Rails.application.config.plaid_eu
+      Provider::Plaid.new(Rails.application.config.plaid_eu, :eu) if Rails.application.config.plaid_eu
     end
 
-    def plaid_provider_for(plaid_item)
-      return nil unless plaid_item
-      plaid_item.eu? ? plaid_eu_provider : plaid_provider
+    def plaid_provider_for_region(region)
+      region.to_sym == :eu ? plaid_eu_provider : plaid_us_provider
     end
   end
 
   private
-    def plaid_provider_for(plaid_item)
-      self.class.plaid_provider_for(plaid_item)
+    def eu?
+      raise "eu? is not implemented for #{self.class.name}"
+    end
+
+    def plaid_provider
+      eu? ? self.class.plaid_eu_provider : self.class.plaid_us_provider
     end
 end