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/engine/metadata-modules/flat-view-field/constants/default-view-field-size.constant.ts

@@ -0,0 +1 @@
+export const DEFAULT_VIEW_FIELD_SIZE = 180;

packages/twenty-server/src/engine/metadata-modules/flat-view-field/services/workspace-flat-view-field-map-cache.service.ts

@@ -10,7 +10,7 @@ import { FlatViewFieldMaps } from 'src/engine/metadata-modules/flat-view-field/t
 import { fromViewFieldEntityToFlatViewField } from 'src/engine/metadata-modules/flat-view-field/utils/from-view-field-entity-to-flat-view-field.util';
 import { ViewFieldEntity } from 'src/engine/metadata-modules/view-field/entities/view-field.entity';
 import { WorkspaceCache } from 'src/engine/workspace-cache/decorators/workspace-cache.decorator';
-import { addFlatEntityToFlatEntityMapsThroughMutationOrThrow } from 'src/engine/workspace-manager/workspace-migration-v2/utils/add-flat-entity-to-flat-entity-maps-through-mutation-or-throw.util';
+import { addFlatEntityToFlatEntityMapsThroughMutationOrThrow } from 'src/engine/workspace-manager/workspace-migration/utils/add-flat-entity-to-flat-entity-maps-through-mutation-or-throw.util';
 
 @Injectable()
 @WorkspaceCache('flatViewFieldMaps')

packages/twenty-server/src/engine/metadata-modules/flat-view-field/utils/from-create-view-field-input-to-flat-view-field-to-create.util.ts

@@ -1,9 +1,9 @@
 import { trimAndRemoveDuplicatedWhitespacesFromObjectStringProperties } from 'twenty-shared/utils';
 import { v4 } from 'uuid';
 
+import { DEFAULT_VIEW_FIELD_SIZE } from 'src/engine/metadata-modules/flat-view-field/constants/default-view-field-size.constant';
 import { type FlatViewField } from 'src/engine/metadata-modules/flat-view-field/types/flat-view-field.type';
 import { type CreateViewFieldInput } from 'src/engine/metadata-modules/view-field/dtos/inputs/create-view-field.input';
-import { DEFAULT_VIEW_FIELD_SIZE } from 'src/engine/workspace-manager/standard-objects-prefill-data/views/constants/DEFAULT_VIEW_FIELD_SIZE';
 
 export type FromCreateViewFieldInputToFlatViewFieldToCreateArgs = {
   createViewFieldInput: CreateViewFieldInput;