DEV: Introduce hidden s3_inventory_bucket site setting (#27304)

This commit introduces a hidden `s3_inventory_bucket` site setting which
replaces the `enable_s3_inventory` and `s3_configure_inventory_policy`
site setting.

The reason `enable_s3_inventory` and `s3_configure_inventory_policy`
site settings are removed is because this feature has technically been
broken since it was introduced. When the `enable_s3_inventory` feature
is turned on, the app will because configure a daily inventory policy for the
`s3_upload_bucket` bucket and store the inventories under a prefix in
the bucket. The problem here is that once the inventories are created,
there is nothing cleaning up all these inventories so whoever that has
enabled this feature would have been paying the cost of storing a whole
bunch of inventory files which are never used. Given that we have not
received any complains about inventory files inflating S3 storage costs,
we think that it is very likely that this feature is no longer being
used and we are looking to drop support for this feature in the not too
distance future.

For now, we will still support a hidden `s3_inventory_bucket` site
setting which site administrators can configure via the
`DISCOURSE_S3_INVENTORY_BUCKET` env.

app/jobs/regular/update_s3_inventory.rb

@@ -1,21 +0,0 @@
-# frozen_string_literal: true
-
-require "s3_inventory"
-
-module Jobs
-  # if upload bucket changes or inventory bucket changes we want to update s3 bucket policy and inventory configuration
-  class UpdateS3Inventory < ::Jobs::Base
-    def execute(args)
-      unless SiteSetting.enable_s3_inventory? && SiteSetting.Upload.enable_s3_uploads &&
-               SiteSetting.s3_configure_inventory_policy
-        return
-      end
-
-      %i[upload optimized].each do |type|
-        s3_inventory = S3Inventory.new(Discourse.store.s3_helper, type)
-        s3_inventory.update_bucket_policy if type == :upload
-        s3_inventory.update_bucket_inventory_configuration
-      end
-    end
-  end
-end

app/jobs/scheduled/ensure_s3_uploads_existence.rb

@@ -15,10 +15,6 @@ module Jobs
       end
     end
 
-    def s3_helper
-      Discourse.store.s3_helper
-    end
-
     def prepare_for_all_sites
       inventory = S3Inventory.new(s3_helper, :upload)
       @db_inventories = inventory.prepare_for_all_sites
@@ -26,8 +22,7 @@ module Jobs
     end
 
     def execute(args)
-      return if !SiteSetting.enable_s3_inventory
-      require "s3_inventory"
+      return if (s3_inventory_bucket = SiteSetting.s3_inventory_bucket).blank?
 
       if !@db_inventories && Rails.configuration.multisite && GlobalSetting.use_s3?
         prepare_for_all_sites
@@ -37,13 +32,13 @@ module Jobs
            preloaded_inventory_file =
              @db_inventories[RailsMultisite::ConnectionManagement.current_db]
         S3Inventory.new(
-          s3_helper,
           :upload,
+          s3_inventory_bucket:,
           preloaded_inventory_file: preloaded_inventory_file,
           preloaded_inventory_date: @inventory_date,
         ).backfill_etags_and_list_missing
       else
-        S3Inventory.new(s3_helper, :upload).backfill_etags_and_list_missing
+        S3Inventory.new(:upload, s3_inventory_bucket:).backfill_etags_and_list_missing
       end
     end
   end