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-tab/utils/transform-page-layout-tab-entity-to-flat-page-layout-tab.util.ts

@@ -13,8 +13,7 @@ export const transformPageLayoutTabEntityToFlatPageLayoutTab = (
     position: pageLayoutTabEntity.position,
     pageLayoutId: pageLayoutTabEntity.pageLayoutId,
     workspaceId: pageLayoutTabEntity.workspaceId,
-    universalIdentifier:
-      pageLayoutTabEntity.universalIdentifier ?? pageLayoutTabEntity.id,
+    universalIdentifier: pageLayoutTabEntity.universalIdentifier,
     applicationId: pageLayoutTabEntity.applicationId,
     widgetIds: pageLayoutTabEntity.widgets.map((widget) => widget.id),
   };