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/command/command.module.ts

@@ -5,17 +5,13 @@ import { DatabaseCommandModule } from 'src/database/commands/database-command.mo
 import { FieldMetadataModule } from 'src/engine/metadata-modules/field-metadata/field-metadata.module';
 import { ObjectMetadataModule } from 'src/engine/metadata-modules/object-metadata/object-metadata.module';
 import { WorkspaceCleanerModule } from 'src/engine/workspace-manager/workspace-cleaner/workspace-cleaner.module';
-import { WorkspaceMigrationRunnerCommandsModule } from 'src/engine/workspace-manager/workspace-migration-runner/commands/workspace-migration-runner-commands.module';
-import { WorkspaceSyncMetadataCommandsModule } from 'src/engine/workspace-manager/workspace-sync-metadata/commands/workspace-sync-metadata-commands.module';
 import { MessagingMessageCleanerModule } from 'src/modules/messaging/message-cleaner/messaging-message-cleaner.module';
 
 @Module({
   imports: [
     AppModule,
-    WorkspaceSyncMetadataCommandsModule,
     DatabaseCommandModule,
     MessagingMessageCleanerModule,
-    WorkspaceMigrationRunnerCommandsModule,
     ObjectMetadataModule,
     FieldMetadataModule,
     WorkspaceCleanerModule,