fix: Remove many to many relation option (#7360)

## Description

- This PR addresses the issue #7359

packages/twenty-front/src/modules/settings/data-model/constants/RelationTypes.ts

@@ -1,6 +1,5 @@
 import {
   IconComponent,
-  IllustrationIconManyToMany,
   IllustrationIconOneToMany,
   IllustrationIconOneToOne,
 } from 'twenty-ui';
@@ -35,11 +34,4 @@ export const RELATION_TYPES: Record<
     imageSrc: OneToManySvg,
     isImageFlipped: true,
   },
-  // Not supported yet
-  [RelationDefinitionType.ManyToMany]: {
-    label: 'Belongs to many',
-    Icon: IllustrationIconManyToMany,
-    imageSrc: OneToManySvg,
-    isImageFlipped: true,
-  },
 };