DEV: Housekeeping for CleanUpUploads job (#24361)

Followup to 9db8f00b3d, we
don't need this dead code any more. Also made some minor
improvements and comments.

spec/fabricators/reviewable_fabricator.rb

@@ -12,6 +12,7 @@ Fabricator(:reviewable) do
   category
   score 1.23
   payload { { list: [1, 2, 3], name: "bandersnatch" } }
+  status { :pending }
 end
 
 Fabricator(:reviewable_queued_post_topic, class_name: :reviewable_queued_post) do

spec/jobs/clean_up_uploads_spec.rb

@@ -289,6 +289,7 @@ RSpec.describe Jobs::CleanUpUploads do
       payload: {
         raw: "#{upload.short_url}\n#{upload2.short_url}",
       },
+      status: :pending,
     )
 
     Fabricate(
@@ -296,7 +297,7 @@ RSpec.describe Jobs::CleanUpUploads do
       payload: {
         raw: "#{upload3.short_url}",
       },
-      status: Reviewable.statuses[:rejected],
+      status: :rejected,
     )
 
     Jobs::CleanUpUploads.new.execute(nil)