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-role/utils/from-standard-role-definition-to-flat-role.util.ts

@@ -1,25 +0,0 @@
-import { removePropertiesFromRecord } from 'twenty-shared/utils';
-import { v4 } from 'uuid';
-
-import { type FlatRole } from 'src/engine/metadata-modules/flat-role/types/flat-role.type';
-import { type StandardRoleDefinition } from 'src/engine/workspace-manager/workspace-sync-metadata/standard-roles/types/standard-role-definition.interface';
-
-export const fromStandardRoleDefinitionToFlatRole = (
-  standardRoleDefinition: StandardRoleDefinition,
-  workspaceId: string,
-): FlatRole => {
-  const createdAt = new Date().toISOString();
-
-  return {
-    ...removePropertiesFromRecord(standardRoleDefinition, ['permissionFlags']),
-    id: v4(),
-    workspaceId,
-    universalIdentifier: standardRoleDefinition.standardId || v4(),
-    createdAt,
-    updatedAt: createdAt,
-    permissionFlagIds: [],
-    fieldPermissionIds: [],
-    objectPermissionIds: [],
-    roleTargetIds: [],
-  };
-};