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-field-metadata/utils/from-field-metadata-entity-to-flat-field-metadata.util.ts

@@ -18,11 +18,7 @@ export const fromFieldMetadataEntityToFlatFieldMetadata = <
 
   return {
     ...fieldMetadataWithoutRelations,
-    // TODO remove once MakeFieldMetadataUniversalIdentifierAndApplicationIdNotNullableMigrationCommand has been run once
-    universalIdentifier:
-      fieldMetadataWithoutRelations.universalIdentifier ??
-      fieldMetadataWithoutRelations.standardId ??
-      fieldMetadataWithoutRelations.id,
+    universalIdentifier: fieldMetadataWithoutRelations.universalIdentifier,
     createdAt: fieldMetadataWithoutRelations.createdAt.toISOString(),
     updatedAt: fieldMetadataWithoutRelations.updatedAt.toISOString(),
     kanbanAggregateOperationViewIds:

packages/twenty-server/src/engine/metadata-modules/flat-field-metadata/utils/get-default-flat-field-metadata-from-create-field-input.util.ts

@@ -1,4 +1,5 @@
 import { extractAndSanitizeObjectStringFields } from 'twenty-shared/utils';
+import { v4 } from 'uuid';
 
 import { type CreateFieldInput } from 'src/engine/metadata-modules/field-metadata/dtos/create-field.input';
 import { generateDefaultValue } from 'src/engine/metadata-modules/field-metadata/utils/generate-default-value';
@@ -48,8 +49,7 @@ export const getDefaultFlatFieldMetadata = ({
     standardId: createFieldInput.standardId ?? null,
     standardOverrides: null,
     type: createFieldInput.type,
-    universalIdentifier:
-      createFieldInput.universalIdentifier ?? fieldMetadataId,
+    universalIdentifier: createFieldInput.universalIdentifier ?? v4(),
     workspaceId,
     options: createFieldInput.options ?? null,
     defaultValue: defaultValue ?? generateDefaultValue(createFieldInput.type),