fix(server): run 2-14 standard relation label/icon heal as a system build (#21667)

## Problem

The `2-14:fix-standard-relation-field-labels-icons` workspace upgrade
command aborts the upgrade, failing for every workspace that has drift
to heal with:

```
FIELD_MUTATION_NOT_ALLOWED: System fields only allow updating: universalSettings, isActive. Forbidden properties: icon
```

The default relation fields it heals (note/task/attachment/timeline) on
standard objects are **system-owned**. The flat-field-metadata validator
forbids mutating any property other than `universalSettings`/`isActive`
on a system field **unless the migration runs as a system build**
(`buildOptions.isSystemBuild`). The command omitted `isSystemBuild`, so
it defaulted to `false` and the heal was rejected.

## Fix

Pass `isSystemBuild: true` when building the heal migration — consistent
with every other standard-metadata upgrade command (2-3, 2-5, 2-7, 2-8,
2-9, 2-10, 2-13, other 2-14 commands).

## Notes

- Follow-up to #21658, which added the error-surfacing diagnostics that
revealed this root cause but did not include this fix.
- `label` and `icon` are both in
`FLAT_FIELD_METADATA_RELATION_PROPERTIES_TO_COMPARE`, so the
relation-field validator (not gated on `isSystemBuild`) already permits
them — the system-build flag was the only blocker.
- Dry-run returns before the build step, so this only manifests on real
runs.


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packages/twenty-server/src/database/commands/upgrade-version-command/2-14/2-14-workspace-command-1799000040000-fix-standard-relation-field-labels-icons.command.ts

@@ -132,6 +132,9 @@ export class FixStandardRelationFieldLabelsIconsCommand extends ActiveOrSuspende
           workspaceId,
           applicationUniversalIdentifier:
             twentyStandardFlatApplication.universalIdentifier,
+          // These default relation fields are system-owned; mutating their
+          // label/icon is only permitted under a system build.
+          isSystemBuild: true,
         },
       );