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

@@ -2,7 +2,7 @@ import { type FieldMetadataType } from 'twenty-shared/types';
 import { removePropertiesFromRecord } from 'twenty-shared/utils';
 
 import { type FieldMetadataEntity } from 'src/engine/metadata-modules/field-metadata/field-metadata.entity';
-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 FlatFieldMetadata } from 'src/engine/metadata-modules/flat-field-metadata/types/flat-field-metadata.type';
 
 export const fromFieldMetadataEntityToFlatFieldMetadata = <
@@ -13,9 +13,7 @@ export const fromFieldMetadataEntityToFlatFieldMetadata = <
 ): FlatFieldMetadata => {
   const fieldMetadataWithoutRelations = removePropertiesFromRecord(
     fieldMetadataEntity,
-    Object.keys(
-      ALL_METADATA_RELATION_PROPERTIES.fieldMetadata,
-    ) as (keyof typeof ALL_METADATA_RELATION_PROPERTIES.fieldMetadata)[],
+    getMetadataEntityRelationProperties('fieldMetadata'),
   );
 
   return {