Identification cleanup (#17301)

# Introduction

following https://github.com/twentyhq/twenty/pull/17279
As we've finally identified all the syncable metadata entities, which
means they're expected to have non nullable applicationId and
universalIdentifier at pg_level we can remove previous retro comp
universalIdentifier fallbacking and update the dto too

~~This needs IdentifyRemainingEntitiesMetadataCommand and
MakeRemainingEntitiesUniversalIdentifierAndApplicationIdNotNullableMigrationCommand
to be run~~
```ts
[Nest] 197  - 01/21/2026, 3:08:35 PM     LOG [MakeRemainingEntitiesUniversalIdentifierAndApplicationIdNotNullableMigrationCommand] Successfully run MakeRemainingEntitiesUniversalIdentifierAndApplicationIdNotNullableMigrationCommand
```

packages/twenty-server/src/engine/metadata-modules/flat-page-layout-widget/utils/from-page-layout-widget-entity-to-flat-page-layout-widget.util.ts

@@ -18,8 +18,7 @@ export const fromPageLayoutWidgetEntityToFlatPageLayoutWidget = (
     updatedAt: pageLayoutWidgetEntity.updatedAt.toISOString(),
     deletedAt: pageLayoutWidgetEntity.deletedAt?.toISOString() ?? null,
     universalIdentifier:
-      pageLayoutWidgetEntityWithoutRelations.universalIdentifier ??
-      pageLayoutWidgetEntityWithoutRelations.id,
-    applicationId: pageLayoutWidgetEntityWithoutRelations.applicationId ?? null,
+      pageLayoutWidgetEntityWithoutRelations.universalIdentifier,
+    applicationId: pageLayoutWidgetEntityWithoutRelations.applicationId,
   };
 };