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/workspace-manager/workspace-manager.service.ts

@@ -76,22 +76,6 @@ export class WorkspaceManagerService {
     await this.prefillWorkspaceWithDemoObjects(dataSourceMetadata, workspaceId);
   }
 
-  /**
-   *
-   * Check if the workspace schema has already been created or not
-   *
-   * @param workspaceId
-   * @Returns Promise<boolean>
-   */
-  public async doesDataSourceExist(workspaceId: string): Promise<boolean> {
-    const dataSource =
-      await this.dataSourceService.getDataSourcesMetadataFromWorkspaceId(
-        workspaceId,
-      );
-
-    return dataSource.length > 0;
-  }
-
   /**
    *
    * We are updating the pg_graphql max_rows from 30 (default value) to 60