Revert "Add association Account#own_regional_office"

This reverts commit 2024d3648c.

app/models/account.rb

@@ -14,12 +14,6 @@ class Account < ApplicationRecord
           class_name: 'MembershipApp',
           dependent:  :restrict_with_exception
 
-  has_one :own_regional_office,
-          class_name: 'RegionalOffice',
-          inverse_of: false,
-          through:    :person,
-          source:     :regional_office
-
   has_many :passport_confirmations, dependent: :restrict_with_exception
 
   scope :guests, -> { includes(:user).where(users: { id: nil }) }

spec/models/account_spec.rb

@@ -26,15 +26,6 @@ RSpec.describe Account do
       .dependent(:restrict_with_exception)
   end
 
-  it do
-    is_expected.to \
-      have_one(:own_regional_office)
-      .class_name('RegionalOffice')
-      .inverse_of(false)
-      .through(:person)
-      .source(:regional_office)
-  end
-
   it do
     is_expected.to \
       have_many(:passport_confirmations)