Fix executing the removal of journal_versions

The original version does not work correctly.

db/migrate/20210726070813_remove_journal_versions.rb

@@ -0,0 +1,13 @@
+require_relative './20190724093332_add_journal_versions_table'
+
+# db/migrate/20200522140244_remove_journal_versions_table.rb
+# incorrectly removes journal_versions
+class RemoveJournalVersions < ActiveRecord::Migration[6.1]
+  def up
+    ::AddJournalVersionsTable.new.down
+  end
+
+  def down
+    # Nothing to do
+  end
+end