Use Estonian reference number format instead of ISO 11649

spec/factories/invoice.rb

@@ -9,6 +9,7 @@ FactoryBot.define do
     seller_street { 'Paldiski mnt. 123' }
     vat_rate 0.2
     buyer { FactoryBot.create(:registrar) }
+    sequence(:reference_no) { |n| "1234#{n}" }
 
     after :build do |invoice|
       invoice.invoice_items << FactoryBot.create_pair(:invoice_item)

spec/factories/registrar.rb

@@ -11,6 +11,7 @@ FactoryBot.define do
     country_code 'US'
     accounting_customer_code 'test'
     language 'en'
+    sequence(:reference_no) { |n| "1234#{n}" }
 
     factory :registrar_with_unlimited_balance do
       after :create do |registrar|

spec/models/bank_statement_spec.rb

@@ -36,7 +36,7 @@ describe BankStatement do
     end
 
     it 'should not bind transactions with invalid match data' do
-      r = create(:registrar, reference_no: 'RF7086666663')
+      r = create(:registrar, reference_no: '1234')
 
       create(:account, registrar: r, account_type: 'cash', balance: 0)
 
@@ -50,7 +50,7 @@ describe BankStatement do
         }),
         create(:bank_transaction, {
           sum: 240.0,
-          reference_no: 'RF7086666663',
+          reference_no: '1234',
           description: 'Invoice no. 4948934'
         })
       ])

spec/models/bank_transaction_spec.rb

@@ -35,7 +35,7 @@ describe BankTransaction do
     end
 
     it 'should not bind transaction with mismatching sums' do
-      r = create(:registrar, reference_no: 'RF7086666663')
+      r = create(:registrar)
       invoice = r.issue_prepayment_invoice(200, 'add some money')
 
       bt = create(:bank_transaction, { sum: 10 })
@@ -45,7 +45,7 @@ describe BankTransaction do
     end
 
     it 'should not bind transaction with cancelled invoice' do
-      r = create(:registrar, reference_no: 'RF7086666663')
+      r = create(:registrar)
       invoice = r.issue_prepayment_invoice(200, 'add some money')
       invoice.cancel