Remove sync-metadata and IS_WORKSPACE_CREATION_V2_ENABLED feature flag (#16997)

# Introduction
Followup of
https://github.com/twentyhq/twenty/pull/17001#pullrequestreview-3638508738
close https://github.com/twentyhq/core-team-issues/issues/1910

We've completely decom the `sync-metadata` in production. We're now then
removing its implementation in favor of the v2.

## TODO:
- [x] Remove sync-metadata implem and commands
- [x] Remove workspace decorators 
- [x] Type each deprecated field to deprecated on their workspaceEntity
- [x] Remove the `workspace-sync-metadata` folder entirely
- [x] remove workspace migration
- [x] workspace migration removal migration
- [x] remove the `v2` references from workspace manager file names
- [x] remove the `v2` references from workspace manager modules
- [ ] Double check impact on translation file path updates


## Note
- Removed the gate logic
- Remains some service v2 naming, serverless needs to be migrated on v2
fully
- Removed workspaceMigration service app health consumption, making it
always returning up ( no more down ) cc @FelixMalfait ( quite obsolete
health check now, will require complete refactor once we introduce inter
app dependency etc )

packages/twenty-server/src/database/commands/database-command.module.ts

@@ -24,7 +24,7 @@ import { WorkspaceCacheStorageModule } from 'src/engine/workspace-cache-storage/
 import { DevSeederModule } from 'src/engine/workspace-manager/dev-seeder/dev-seeder.module';
 import { WorkspaceCleanerModule } from 'src/engine/workspace-manager/workspace-cleaner/workspace-cleaner.module';
 import { WorkspaceManagerModule } from 'src/engine/workspace-manager/workspace-manager.module';
-import { WorkspaceMigrationV2Module } from 'src/engine/workspace-manager/workspace-migration-v2/workspace-migration-v2.module';
+import { WorkspaceMigrationModule } from 'src/engine/workspace-manager/workspace-migration/workspace-migration.module';
 import { CalendarEventImportManagerModule } from 'src/modules/calendar/calendar-event-import-manager/calendar-event-import-manager.module';
 import { MessagingImportManagerModule } from 'src/modules/messaging/message-import-manager/messaging-import-manager.module';
 import { WorkflowRunQueueModule } from 'src/modules/workflow/workflow-runner/workflow-run-queue/workflow-run-queue.module';
@@ -54,7 +54,7 @@ import { AutomatedTriggerModule } from 'src/modules/workflow/workflow-trigger/au
     CronTriggerModule,
     DatabaseEventTriggerModule,
     WorkspaceCleanerModule,
-    WorkspaceMigrationV2Module,
+    WorkspaceMigrationModule,
     TrashCleanupModule,
     PublicDomainModule,
   ],