fix(dcim): Avoid clearing scope on clone

ScopedForm._set_scoped_values() cleared initial['scope'] whenever the
scope_type differed from the instance value. During cloning (unsaved
instance), this runs on the initial GET and wipes the pre-filled scope,
forcing the user to re-select it.

Only clear the scope when editing an existing object (instance.pk set)
and the scope type has actually changed.

Fixes #21202

netbox/dcim/forms/mixins.py

@@ -75,7 +75,7 @@ class ScopedForm(forms.Form):
             except ObjectDoesNotExist:
                 pass
 
-            if self.instance and scope_type_id != self.instance.scope_type_id:
+            if self.instance and self.instance.pk and scope_type_id != self.instance.scope_type_id:
                 self.initial['scope'] = None
 
         else: