Refactor new relation sync (#11711)

In this PR:
- this should fix the sync metadata for new relation system

This goes with the recent PR:
https://github.com/twentyhq/twenty/pull/11725

What we want:
- ONE_TO_MANY relations should have no joinColumn and no onDelete
- MANY_TO_ONE should have both

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

@@ -100,7 +100,6 @@ export class ObjectMetadataFieldRelationService {
         ...sourceFieldMetadata,
         settings: {
           relationType: RelationType.ONE_TO_MANY,
-          onDelete: RelationOnDeleteAction.CASCADE,
         },
         relationTargetObjectMetadataId: targetObjectMetadata.id,
         relationTargetFieldMetadataId: targetFieldMetadata.id,