Remove DataSourceService and clean up datasource migration logic (#19532)

## Summary

- **Drop the `objectMetadata.dataSourceId` foreign key and index** via a
1-22 fast instance command — column kept nullable for data preservation
- **Delete `DataSourceService`, `DataSourceModule`, and
`DataSourceException`** — all code now uses `workspace.databaseSchema`
directly
- **Remove `IS_DATASOURCE_MIGRATED` feature flag** from default flags
and all branching logic
- **Simplify workspace/object creation pipelines** —
`WorkspaceManagerService`, `DevSeederService`, and the object creation
action handler no longer route through `DataSourceService`
- **Keep `DataSourceEntity` and the `dataSource` table** for historical
data — entity stripped of all ORM relations

packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.module.ts

@@ -2,19 +2,12 @@ import { Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 
 import { TypeORMModule } from 'src/database/typeorm/typeorm.module';
-import { FeatureFlagModule } from 'src/engine/core-modules/feature-flag/feature-flag.module';
 import { WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
-import { DataSourceModule } from 'src/engine/metadata-modules/data-source/data-source.module';
 
 import { WorkspaceDataSourceService } from './workspace-datasource.service';
 
 @Module({
-  imports: [
-    TypeOrmModule.forFeature([WorkspaceEntity]),
-    TypeORMModule,
-    FeatureFlagModule,
-    DataSourceModule,
-  ],
+  imports: [TypeOrmModule.forFeature([WorkspaceEntity]), TypeORMModule],
   exports: [WorkspaceDataSourceService],
   providers: [WorkspaceDataSourceService],
 })

packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.service.ts

@@ -3,13 +3,10 @@ import { InjectDataSource, InjectRepository } from '@nestjs/typeorm';
 
 import { msg } from '@lingui/core/macro';
 import { isNonEmptyString } from '@sniptt/guards';
-import { FeatureFlagKey } from 'twenty-shared/types';
 import { type DataSource, type EntityManager, Repository } from 'typeorm';
 
-import { FeatureFlagService } from 'src/engine/core-modules/feature-flag/services/feature-flag.service';
 import { TwentyConfigService } from 'src/engine/core-modules/twenty-config/twenty-config.service';
 import { WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
-import { DataSourceService } from 'src/engine/metadata-modules/data-source/data-source.service';
 import {
   PermissionsException,
   PermissionsExceptionCode,
@@ -27,8 +24,6 @@ export class WorkspaceDataSourceService {
     private readonly workspaceRepository: Repository<WorkspaceEntity>,
     @InjectDataSource()
     private readonly coreDataSource: DataSource,
-    private readonly featureFlagService: FeatureFlagService,
-    private readonly dataSourceService: DataSourceService,
     private readonly twentyConfigService: TwentyConfigService,
   ) {}
 
@@ -43,26 +38,12 @@ export class WorkspaceDataSourceService {
   }
 
   public async checkSchemaExists(workspaceId: string) {
-    const isDataSourceMigrated = await this.featureFlagService.isFeatureEnabled(
-      FeatureFlagKey.IS_DATASOURCE_MIGRATED,
-      workspaceId,
-    );
+    const workspace = await this.workspaceRepository.findOne({
+      select: ['databaseSchema'],
+      where: { id: workspaceId },
+    });
 
-    if (isDataSourceMigrated) {
-      const workspace = await this.workspaceRepository.findOne({
-        select: ['databaseSchema'],
-        where: { id: workspaceId },
-      });
-
-      return isNonEmptyString(workspace?.databaseSchema);
-    }
-
-    const dataSources =
-      await this.dataSourceService.getDataSourcesMetadataFromWorkspaceId(
-        workspaceId,
-      );
-
-    return dataSources.length > 0;
+    return isNonEmptyString(workspace?.databaseSchema);
   }
 
   /**