BURs: remove old single alias/implication pruning code.

* Rename TagChangeRequestPruner to BulkUpdateRequestPruner.
* Remove old code for pruning individual alias / implication requests.

test/unit/bulk_update_request_pruner_test.rb

@@ -0,0 +1,25 @@
+require 'test_helper'
+
+class BulkUpdateRequestPrunerTest < ActiveSupport::TestCase
+  context '#warn_old' do
+    should "update the forum topic for a bulk update request" do
+      forum_topic = as(create(:user)) { create(:forum_topic) }
+      bur = create(:bulk_update_request, status: "pending", forum_topic: forum_topic, created_at: (TagRelationship::EXPIRY_WARNING + 1).days.ago)
+
+      BulkUpdateRequestPruner.warn_old
+      assert_equal("pending", bur.reload.status)
+      assert_match(/pending automatic rejection/, ForumPost.last.body)
+    end
+  end
+
+  context '#reject_expired' do
+    should "reject the bulk update request" do
+      forum_topic = as(create(:user)) { create(:forum_topic) }
+      bur = create(:bulk_update_request, status: "pending", forum_topic: forum_topic, created_at: (TagRelationship::EXPIRY + 1).days.ago)
+
+      BulkUpdateRequestPruner.reject_expired
+      assert_equal("rejected", bur.reload.status)
+      assert_match(/rejected because it was not approved within 60 days/, bur.forum_post.body)
+    end
+  end
+end