Fix custom object renaming (#8746)

Currently when renaming an object, we execute
```
await this.fieldMetadataRepository
                    .findOneByOrFail({
                      name: existingObjectMetadata.nameSingular,
                      label: existingObjectMetadata.labelSingular,
                      objectMetadataId: relatedObject.id,
                      workspaceId: workspaceId,
                    })
```
to find the standard relation fields. 
This would throw an error if the label solely was update beforehand
without updating the name too: in that case we will not have migrated
the label of the standard relation fields (which is maybe a mistake?
@Weiko wdyt?).
Let's remove it.

packages/twenty-server/src/engine/metadata-modules/object-metadata/services/object-metadata-migration.service.ts

@@ -165,12 +165,11 @@ export class ObjectMetadataMigrationService {
                 });
 
               if (relatedObject) {
-                // 1. Update to and from relation fieldMetadata)
+                // 1. Update to and from relation fieldMetadata
                 const toFieldRelationFieldMetadataId =
                   await this.fieldMetadataRepository
                     .findOneByOrFail({
                       name: existingObjectMetadata.nameSingular,
-                      label: existingObjectMetadata.labelSingular,
                       objectMetadataId: relatedObject.id,
                       workspaceId: workspaceId,
                     })