post disapprovals: refactor disapproval reasons.

* Factor out reasons into a constant
* Change column default and eliminate unused `legacy` reason.

test/factories/post_disapproval.rb

@@ -2,7 +2,7 @@ FactoryBot.define do
   factory(:post_disapproval) do
     user
     post
-    reason { %w(breaks_rules poor_quality disinterest).sample }
+    reason { PostDisapproval::REASONS.sample }
     message { FFaker::Lorem.sentence }
   end
 end

test/system/autocomplete_test.rb

@@ -45,8 +45,8 @@ class AutocompleteTest < ApplicationSystemTestCase
         assert_metatag_autocomplete_equals(%w[rating note status], "locked")
         assert_metatag_autocomplete_equals(%w[safe questionable explicit], "rating")
         assert_metatag_autocomplete_equals(%w[gif jpg mp4 png swf webm zip], "filetype")
-        assert_metatag_autocomplete_equals(%w[any none disinterest poor_quality breaks_rules], "disapproval")
         assert_metatag_autocomplete_equals(%w[active any banned deleted flagged modqueue pending unmoderated], "status")
+        assert_metatag_autocomplete_equals(PostDisapproval::REASONS, "disapproval")
       end
 
       should "work for username metatags" do

test/unit/post_disapproval_test.rb

@@ -26,7 +26,7 @@ class PostDisapprovalTest < ActiveSupport::TestCase
 
       context "made by alice" do
         setup do
-          @disapproval = PostDisapproval.create(:user => @alice, :post => @post_1)
+          @disapproval = create(:post_disapproval, user: @alice, post: @post_1)
         end
 
         context "when the current user is alice" do
@@ -57,9 +57,7 @@ class PostDisapprovalTest < ActiveSupport::TestCase
         setup do
           @post = FactoryBot.create(:post)
           @user = FactoryBot.create(:user)
-          travel_to(2.months.ago) do
-            @disapproval = PostDisapproval.create(:user => @user, :post => @post)
-          end
+          @disapproval = create(:post_disapproval, user: @user, post: @post, created_at: 2.months.ago)
         end
 
         should "be pruned" do