Revert "add down fn"

This reverts commit a6e92ff.

Author: RobertJoonas

priv/ingest_repo/migrations/20241216133031_add_scroll_depth_to_imported_pages.exs

@@ -1,21 +1,17 @@
 defmodule Plausible.IngestRepo.Migrations.AddScrollDepthToImportedPages do
   use Ecto.Migration
 
-  @on_cluster Plausible.MigrationUtils.on_cluster_statement("imported_pages")
-
   def up do
+    on_cluster = Plausible.MigrationUtils.on_cluster_statement("imported_pages")
+
     execute """
     ALTER TABLE imported_pages
-    #{@on_cluster}
+    #{on_cluster}
     ADD COLUMN scroll_depth UInt8 DEFAULT 255
     """
   end
 
   def down do
-    execute """
-    ALTER TABLE imported_pages
-    #{@on_cluster}
-    DROP COLUMN scroll_depth
-    """
+    raise "Irreversible"
   end
 end