Delete calculator currency values from db [migration]

This depends on openfoodfoundation#10318 being deployed first.

db/migrate/20230126233821_delete_calculator_currency_from_spree_preferences.rb

@@ -0,0 +1,15 @@
+class DeleteCalculatorCurrencyFromSpreePreferences < ActiveRecord::Migration[6.1]
+  class SpreePreference < ActiveRecord::Base
+  end
+
+  def up
+    # Delete all currency preferences for calculators, they are no longer used.
+    rows = SpreePreference.where("key like '/calculator%/currency/%'").delete_all
+    puts "#{rows} rows deleted."
+  end
+
+  def down
+    # Sorry, the data was deleted!
+    raise ActiveRecord::IrreversibleMigration
+  end
+end