Centralize metadata relations constant + simplification (#16901)

# Introduction
As we introduced a new grain on relation extraction thanks to low level
`SyncableEntity` and `WorkspaceRelatedEntity` we're able to strictly
typesafe extract metadata entity

The new constant centralizes both many to one and one to many constants
metadata entity constants in a more strictly typesafe way. Remains only
the flatEntityForeignKey aggregator which has to be chosen manually
across all available targeted flat entity ids properties

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

@@ -1,6 +1,6 @@
 import { removePropertiesFromRecord } from 'twenty-shared/utils';
 
-import { ALL_METADATA_RELATION_PROPERTIES } from 'src/engine/metadata-modules/flat-entity/constant/all-metadata-relations-properties.constant';
+import { getMetadataEntityRelationProperties } from 'src/engine/metadata-modules/flat-entity/utils/get-metadata-entity-relation-properties.util';
 import { type FlatObjectMetadata } from 'src/engine/metadata-modules/flat-object-metadata/types/flat-object-metadata.type';
 import { type ObjectMetadataEntity } from 'src/engine/metadata-modules/object-metadata/object-metadata.entity';
 
@@ -9,9 +9,7 @@ export const fromObjectMetadataEntityToFlatObjectMetadata = (
 ): FlatObjectMetadata => {
   const objectMetadataEntityWithoutRelations = removePropertiesFromRecord(
     objectMetadataEntity,
-    Object.keys(
-      ALL_METADATA_RELATION_PROPERTIES.objectMetadata,
-    ) as (keyof typeof ALL_METADATA_RELATION_PROPERTIES.objectMetadata)[],
+    getMetadataEntityRelationProperties('objectMetadata'),
   );
 
   return {