Remove unused icons from Spree:Taxon

The icons are not used any more and the default icon file never existed
in our code base (only in Spree when we depended on that).

And it's better to remove this clutter before migrating those files to
Active Storage.

We are keeping the icon files in storage as a backup. The whole folder
`/spree/taxons` can be deleted when desired. But storage is cheap.

app/models/spree/taxon.rb

@@ -2,8 +2,6 @@
 
 module Spree
   class Taxon < ApplicationRecord
-    include Spree::Core::S3Support
-
     acts_as_nested_set dependent: :destroy
 
     belongs_to :taxonomy, class_name: 'Spree::Taxonomy', touch: true
@@ -14,15 +12,6 @@ module Spree
 
     validates :name, presence: true
 
-    has_attached_file :icon,
-                      styles: { mini: '32x32>', normal: '128x128>' },
-                      default_style: :mini,
-                      url: '/spree/taxons/:id/:style/:basename.:extension',
-                      path: ':rails_root/public/spree/taxons/:id/:style/:basename.:extension',
-                      default_url: '/assets/default_taxon.png'
-
-    supports_s3 :icon
-
     # Indicate which filters should be used for this taxon
     def applicable_filters
       []

app/views/spree/admin/taxonomies/_taxon.html.haml

@@ -2,6 +2,6 @@
   %ul
     - taxon.children.each do |child|
       %li{id: "#{child.id}", rel: "taxon"}
-        %a{href: "#", style: "background-image: url(#{child.icon.url});"}= child.name
+        %a{href: "#"}= child.name
         - if child.children.length > 0
           = render partial: 'taxon', locals: { taxon: child }

db/migrate/20220407051248_remove_icon_from_spree_taxons.rb

@@ -0,0 +1,8 @@
+class RemoveIconFromSpreeTaxons < ActiveRecord::Migration[6.1]
+  def change
+    remove_column :spree_taxons, :icon_file_name, :string
+    remove_column :spree_taxons, :icon_content_type, :string
+    remove_column :spree_taxons, :icon_file_size, :integer
+    remove_column :spree_taxons, :icon_updated_at, :datetime
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_02_21_165207) do
+ActiveRecord::Schema.define(version: 2022_04_07_051248) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -976,10 +976,6 @@ ActiveRecord::Schema.define(version: 2022_02_21_165207) do
     t.datetime "updated_at", null: false
     t.integer "lft"
     t.integer "rgt"
-    t.string "icon_file_name", limit: 255
-    t.string "icon_content_type", limit: 255
-    t.integer "icon_file_size"
-    t.datetime "icon_updated_at"
     t.text "description"
     t.string "meta_title", limit: 255
     t.string "meta_description", limit: 255