Use zope.deferredimport.deprecated for RENAME_AFTER_CREATION_ATTEMPTS

Mark the backwards-compat re-export with a deprecation warning so it
can be removed in Plone 7. Consumers should import from
plone.app.users.utils instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jensens

src/plone/app/users/browser/register.py

@@ -7,7 +7,6 @@
 from plone.app.users.utils import generate_login_name as _generate_login_name
 from plone.app.users.utils import generate_user_id as _generate_user_id
 from plone.app.users.utils import notifyWidgetActionExecutionError
-from plone.app.users.utils import RENAME_AFTER_CREATION_ATTEMPTS  # noqa: F401
 from plone.autoform.form import AutoExtensibleForm
 from plone.base import PloneMessageFactory as _
 from plone.base.interfaces import ISecuritySchema
@@ -29,10 +28,16 @@
 from zope.component import getAdapter
 from zope.component import getMultiAdapter
 from zope.component import getUtility
+from zope.deferredimport import deprecated
 from zope.schema import getFieldNames
 
 import logging
 
+deprecated(
+    "Import from plone.app.users.utils instead.",
+    RENAME_AFTER_CREATION_ATTEMPTS="plone.app.users.utils:RENAME_AFTER_CREATION_ATTEMPTS",
+)
+
 
 def getRegisterSchema():
     schema = getSchema(