Remove deprecated attributes from Proposals

Some fields from Proposals are deprecated and we no longer need them.

db/migrate/20200831113416_remove_deprecated_fields_from_proposals.rb

@@ -0,0 +1,8 @@
+class RemoveDeprecatedFieldsFromProposals < ActiveRecord::Migration[5.1]
+  def change
+    remove_column :proposals, :deprecated_title, :string
+    remove_column :proposals, :deprecated_description, :text
+    remove_column :proposals, :deprecated_summary, :text
+    remove_column :proposals, :deprecated_retired_explanation, :text
+  end
+end

db/schema.rb

@@ -1219,8 +1219,6 @@ ActiveRecord::Schema.define(version: 20200908084257) do
   end
 
   create_table "proposals", id: :serial, force: :cascade do |t|
-    t.string "deprecated_title", limit: 80
-    t.text "deprecated_description"
     t.integer "author_id"
     t.datetime "hidden_at"
     t.integer "flags_count", default: 0
@@ -1233,13 +1231,11 @@ ActiveRecord::Schema.define(version: 20200908084257) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.string "responsible_name", limit: 60
-    t.text "deprecated_summary"
     t.string "video_url"
     t.tsvector "tsv"
     t.integer "geozone_id"
     t.datetime "retired_at"
     t.string "retired_reason"
-    t.text "deprecated_retired_explanation"
     t.integer "community_id"
     t.datetime "published_at"
     t.boolean "selected", default: false