DEV: Drop deprecated Badge#image column (#25536)

We just completed the 3.2 release, which marks a good time to drop some previously deprecated columns.

Since the column has been marked in ignored_columns, it has been inaccessible to application code since then. There's a tiny risk that this might break a Data Explorer query, but given the nature of the column, the years of disuse, and the fact that such a breakage wouldn't be critical, we accept it.

db/post_migrate/20240202052058_drop_badge_image_column.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class DropBadgeImageColumn < ActiveRecord::Migration[7.0]
+  DROPPED_COLUMNS ||= { badges: %i[image] }
+
+  def up
+    DROPPED_COLUMNS.each { |table, columns| Migration::ColumnDropper.execute_drop(table, columns) }
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end