Revert "Allow unconfirmed access for 3 days when OmniAuth sign up"

This reverts commit 1eac19662f.

app/models/user.rb

@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class User < ApplicationRecord
-  ALLOW_UNCONFIRMED_OMNIAUTH_ACCESS_FOR = 3.days
-
   devise(
     :confirmable,
     :database_authenticatable,
@@ -26,13 +24,4 @@ class User < ApplicationRecord
   before_validation do
     self.account ||= Account.new
   end
-
-  def confirmation_period_valid?
-    return if user_omniauths.where(email: email).exists? &&
-              confirmation_sent_at &&
-              confirmation_sent_at.utc >=
-              ALLOW_UNCONFIRMED_OMNIAUTH_ACCESS_FOR.ago
-
-    super
-  end
 end