chore(*): remove unused code (#6781)

The code removed in the PR was flagged as unused by the JetBrains
inspector.

I did a QA on the dev environment but other checks are highly
recommended.

There is one commit by scope to make the review easier.

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine/twenty-orm/datasource/workspace.datasource.ts

@@ -36,8 +36,4 @@ export class WorkspaceDataSource extends DataSource {
   ): WorkspaceEntityManager {
     return new WorkspaceEntityManager(this.internalContext, this, queryRunner);
   }
-
-  getWorkspaceId(): string {
-    return this.internalContext.workspaceId;
-  }
 }