Revert "Don't allow spaces in external billing id"

This reverts commit 39825a9ecb.

app/models/enterprise.rb

@@ -127,9 +127,6 @@ class Enterprise < ApplicationRecord
               message: Spree.t('errors.messages.invalid_instagram_url')
             }, allow_blank: true
   validate :validate_white_label_logo_link
-  validates :external_billing_id,
-            format: { with:/\A\S+\Z/ },
-            allow_blank: true
 
   before_validation :initialize_permalink, if: lambda { permalink.nil? }
   before_validation :set_unused_address_fields

spec/models/enterprise_spec.rb

@@ -415,13 +415,6 @@ RSpec.describe Enterprise do
         expect(e).not_to be_valid
       end
     end
-
-    describe "external_billing_id" do
-      it "does not validate the external_billing_id attribute with a space" do
-        e = build(:enterprise, external_billing_id: 'with spaces')
-        expect(e).not_to be_valid
-      end
-    end
   end
 
   describe "serialisation" do