Remove unused HistoricalData.up_until scope

https://gitlab.com/gitlab-org/gitlab/-/issues/334761#note_653511943

ee/app/models/historical_data.rb

@@ -5,8 +5,6 @@ class HistoricalData < ApplicationRecord
 
   # HistoricalData.during((Time.current - 1.year)..Time.current).average(:active_user_count)
   scope :during, ->(range) { where(recorded_at: range) }
-  # HistoricalData.up_until(Time.current - 1.month).average(:active_user_count)
-  scope :up_until, ->(timestamp) { where("recorded_at <= :timestamp", timestamp: timestamp) }
 
   class << self
     def track!

ee/spec/models/historical_data_spec.rb

@@ -15,12 +15,6 @@ RSpec.describe HistoricalData do
     end
   end
 
-  describe ".up_until" do
-    it "returns the historical data up until the specified date" do
-      expect(described_class.up_until(Date.new(2014, 6, 1)).average(:active_user_count)).to eq(350)
-    end
-  end
-
   describe ".track!" do
     before do
       allow(User).to receive(:billable).and_return([1, 2, 3, 4, 5])