chore(billing) - remove feature flag (#20531)

- remove feature flag
- remove old enforce cap usage logic

packages/twenty-server/src/engine/twenty-orm/entity-manager/workspace-entity-manager.spec.ts

@@ -1,5 +1,4 @@
 import {
-  FeatureFlagKey,
   type FieldMetadataType,
   type ObjectsPermissions,
 } from 'twenty-shared/types';
@@ -241,7 +240,6 @@ describe('WorkspaceEntityManager', () => {
         IS_JUNCTION_RELATIONS_ENABLED: false,
         IS_RECORD_PAGE_LAYOUT_GLOBAL_EDITION_ENABLED: false,
         IS_REST_METADATA_API_NEW_FORMAT_DIRECT: false,
-        [FeatureFlagKey.IS_BILLING_V2_ENABLED]: false,
       },
       userWorkspaceRoleMap: {},
       eventEmitterService: {