Remove unused `Announcement#time_range?` (#28648)

app/models/announcement.rb

@@ -54,10 +54,6 @@ class Announcement < ApplicationRecord
     update!(published: false, scheduled_at: nil)
   end
 
-  def time_range?
-    starts_at? && ends_at?
-  end
-
   def mentions
     @mentions ||= Account.from_text(text)
   end

spec/models/announcement_spec.rb

@@ -113,32 +113,6 @@ describe Announcement do
     end
   end
 
-  describe '#time_range?' do
-    it 'returns false when starts_at and ends_at are missing' do
-      record = Fabricate.build(:announcement, starts_at: nil, ends_at: nil)
-
-      expect(record.time_range?).to be(false)
-    end
-
-    it 'returns false when starts_at is present and ends_at is missing' do
-      record = Fabricate.build(:announcement, starts_at: 5.days.from_now, ends_at: nil)
-
-      expect(record.time_range?).to be(false)
-    end
-
-    it 'returns false when starts_at is missing and ends_at is present' do
-      record = Fabricate.build(:announcement, starts_at: nil, ends_at: 5.days.from_now)
-
-      expect(record.time_range?).to be(false)
-    end
-
-    it 'returns true when starts_at and ends_at are present' do
-      record = Fabricate.build(:announcement, starts_at: 5.days.from_now, ends_at: 10.days.from_now)
-
-      expect(record.time_range?).to be(true)
-    end
-  end
-
   describe '#reactions' do
     context 'with announcement_reactions present' do
       let!(:account) { Fabricate(:account) }