Remove typeorm service (#14116)

## Context
To simplify the way we inject our default datasource, I've recently
removed the token injection that was confusion since we only had once
configured on the module level. Now I'm removing TypeORM service which
allows us to instantiate a new Datasource with the same parameters as
the default one, it was redundant and confusing.

packages/twenty-server/src/engine/workspace-manager/dev-seeder/data/services/dev-seeder-data.service.ts

@@ -1,10 +1,12 @@
 import { Injectable } from '@nestjs/common';
+import { InjectDataSource } from '@nestjs/typeorm';
+
+import { DataSource } from 'typeorm';
 
 import { ObjectMetadataService } from 'src/engine/metadata-modules/object-metadata/object-metadata.service';
 import { type WorkspaceEntityManager } from 'src/engine/twenty-orm/entity-manager/workspace-entity-manager';
 import { computeTableName } from 'src/engine/utils/compute-table-name.util';
 import { shouldSeedWorkspaceFavorite } from 'src/engine/utils/should-seed-workspace-favorite';
-import { WorkspaceDataSourceService } from 'src/engine/workspace-datasource/workspace-datasource.service';
 import {
   CALENDAR_CHANNEL_DATA_SEED_COLUMNS,
   CALENDAR_CHANNEL_DATA_SEEDS,
@@ -196,7 +198,8 @@ const RECORD_SEEDS_CONFIGS = [
 @Injectable()
 export class DevSeederDataService {
   constructor(
-    private readonly workspaceDataSourceService: WorkspaceDataSourceService,
+    @InjectDataSource()
+    private readonly coreDataSource: DataSource,
     private readonly objectMetadataService: ObjectMetadataService,
     private readonly timelineActivitySeederService: TimelineActivitySeederService,
   ) {}
@@ -208,17 +211,10 @@ export class DevSeederDataService {
     schemaName: string;
     workspaceId: string;
   }) {
-    const mainDataSource =
-      await this.workspaceDataSourceService.connectToMainDataSource();
-
-    if (!mainDataSource) {
-      throw new Error('Could not connect to main data source');
-    }
-
     const objectMetadataItems =
       await this.objectMetadataService.findManyWithinWorkspace(workspaceId);
 
-    await mainDataSource.transaction(
+    await this.coreDataSource.transaction(
       async (entityManager: WorkspaceEntityManager) => {
         for (const recordSeedsConfig of RECORD_SEEDS_CONFIGS) {
           const objectMetadata = objectMetadataItems.find(