Deprecate IS_RECORD_TABLE_WIDGET_ENABLED feature flag (#19662)

## Summary
- Removes the `IS_RECORD_TABLE_WIDGET_ENABLED` feature flag, making the
record table widget unconditionally available in dashboard widget type
selection
- The flag was already seeded as `true` for all new workspaces and only
gated UI visibility in one component
(`SidePanelPageLayoutDashboardWidgetTypeSelect`)
- Cleans up the flag from `FeatureFlagKey` enum, dev seeder, and test
mocks

## Analysis
The flag only controlled whether the "View" (Record Table) widget option
appeared in the dashboard widget type selector. The entire record table
widget infrastructure (rendering, creation hooks, GraphQL types,
`RECORD_TABLE` enum in `WidgetType`) is independent of the flag and
fully implemented. No backend logic depends on this flag.

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine/workspace-manager/dev-seeder/core/utils/seed-feature-flags.util.ts

@@ -60,11 +60,6 @@ export const seedFeatureFlags = async ({
         workspaceId: workspaceId,
         value: true,
       },
-      {
-        key: FeatureFlagKey.IS_RECORD_TABLE_WIDGET_ENABLED,
-        workspaceId: workspaceId,
-        value: true,
-      },
     ])
     .execute();
 };