chore(server): remove stray comment in flat-entity-maps spec (#21599)

Follow-up to #21585: removes an explanatory comment in the test that
slipped through before merge.

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packages/twenty-server/src/engine/workspace-manager/workspace-migration/utils/__tests__/add-flat-entity-to-flat-entity-maps-through-mutation-or-throw.util.spec.ts

@@ -55,7 +55,6 @@ describe('addFlatEntityToFlatEntityMapsThroughMutationOrThrow', () => {
       flatEntityMapsToMutate.universalIdentifiersByApplicationId['app-1'];
 
     expect(universalIdentifiers).toEqual(['uid-1', 'uid-2']);
-    // Distinct entities, so each universalIdentifier appears exactly once
     expect(new Set(universalIdentifiers).size).toBe(
       universalIdentifiers?.length,
     );