fix(server): type WasRemovedInUpgrade columns with WasRemovedInUpgrade<> (#21785)

## Context

WasRemovedInUpgrade type brand was introduced in
https://github.com/twentyhq/twenty/pull/21228/changes#diff-1b6d688610669a46b3ee8e3a41b1c7eb0ee03e19146d0d249f95df6e56164a92R15
for the `isCustom` property deprecation.
The @WasRemovedInUpgrade decorator and the WasRemovedInUpgrade<T> type
are meant to go together: the type brand makes the property optional in
every derived flat-entity type, so the column only needs to be declared
on the entity itself. RolePermissionFlagEntity.flag had the decorator
but was typed as a plain PermissionFlagType, forcing the property to be
supplied everywhere.

This PR:
- Types flag as WasRemovedInUpgrade<PermissionFlagType> (matching the
isCustom reference impl on object/field metadata).
- Removes the now-redundant flag from the flat-entity construction
sites, the create input, and the service call site — leaving it only on
the entity. The GraphQL RolePermissionFlagDTO.flag is kept (it's an API
field derived from permissionFlag.key, not the removed column).
- Fixes a latent brand-leak in the flat-entity config type: toStringify
is computed via object-detection, and a branded type reads as an object.
This was harmless for boolean but wrongly forced toStringify: true for
enum/string columns. Added UnwrapWasRemovedInUpgrade<T> and applied it
so the brand is transparent making the pattern work for any type, not
just
booleans.

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packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/all-entity-properties-configuration-by-metadata-name.constant.ts

@@ -1,5 +1,6 @@
 import { type AllMetadataName } from 'twenty-shared/metadata';
 
+import { type UnwrapWasRemovedInUpgrade } from 'src/engine/core-modules/upgrade/decorators/was-removed-in-upgrade.decorator';
 import { type MetadataEntity } from 'src/engine/metadata-modules/flat-entity/types/metadata-entity.type';
 import { type MetadataManyToOneJoinColumn } from 'src/engine/metadata-modules/flat-entity/types/metadata-many-to-one-join-column.type';
 import { type ScalarFlatEntity } from 'src/engine/metadata-modules/flat-entity/types/scalar-flat-entity.type';
@@ -29,9 +30,13 @@ type MetadataEntityPropertyConfiguration<
     toStringify: K extends ExtractJsonbProperties<MetadataEntity<TMetadataName>>
       ? true
       : K extends keyof MetadataEntity<TMetadataName>
-        ? NonNullable<MetadataEntity<TMetadataName>[K]> extends Date
+        ? NonNullable<
+            UnwrapWasRemovedInUpgrade<MetadataEntity<TMetadataName>[K]>
+          > extends Date
           ? false
-          : HasObjectInUnion<MetadataEntity<TMetadataName>[K]>
+          : HasObjectInUnion<
+              UnwrapWasRemovedInUpgrade<MetadataEntity<TMetadataName>[K]>
+            >
         : boolean;
     toCompare: boolean;
     isOverridable?: boolean;