DEV: Set bigint sequences to start at MAX_INT (#28961)

This helps uncover issues with bigint columns that are joined with int
columns. It also introduces a temporary API for plugins to migrate int
columns to bigint in test environment to make tests pass.

plugins/automation/db/migrate/20241010155139_alter_automation_ids_to_bigint.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class AlterAutomationIdsToBigint < ActiveRecord::Migration[7.1]
+  def up
+    change_column :discourse_automation_fields, :automation_id, :bigint
+    change_column :discourse_automation_pending_automations, :automation_id, :bigint
+    change_column :discourse_automation_pending_pms, :automation_id, :bigint
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end