Store home feeds for 7 days instead of 14 (#7354)

* Store home feeds for 7 days instead of 14

Reduces workload for status fan-out to active followers

* Fix test for user model

spec/models/user_spec.rb

@@ -75,7 +75,7 @@ RSpec.describe User, type: :model do
     describe 'inactive' do
       it 'returns a relation of inactive users' do
         specified = Fabricate(:user, current_sign_in_at: 15.days.ago)
-        Fabricate(:user, current_sign_in_at: 13.days.ago)
+        Fabricate(:user, current_sign_in_at: 6.days.ago)
 
         expect(User.inactive).to match_array([specified])
       end