Fix relation creation (#10171)

## Context
We recently introduced a createMany on the field metadata service to
improve seeding performances. This broke relation metadata creation
because it was using a method with the same name that was inherited from
TypeOrmQueryService.

packages/twenty-server/src/engine/metadata-modules/relation-metadata/relation-metadata.service.ts

@@ -93,7 +93,7 @@ export class RelationMetadataService extends TypeOrmQueryService<RelationMetadat
     const toId = uuidV4();
 
     const createdRelationFieldsMetadata =
-      await this.fieldMetadataService.createMany([
+      await this.fieldMetadataRepository.save([
         this.createFieldMetadataForRelationMetadata(
           relationMetadataInput,
           'from',