refactor(reporting): enhance timezone handling and clean up migration

- Updated SQL queries in reporting controllers to join with the timezones table for accurate timezone retrieval.
- Refactored ReportingMembersController to extend ReportingControllerBaseWithTimezone for centralized timezone logic.
- Removed obsolete migration file that added a timezone column to the users table, as it is no longer needed.

worklenz-backend/src/controllers/reporting/reporting-controller-base-with-timezone.ts

@@ -12,7 +12,10 @@ export default abstract class ReportingControllerBaseWithTimezone extends Workle
    * @returns The user's timezone or 'UTC' as default
    */
   protected static async getUserTimezone(userId: string): Promise<string> {
-    const q = `SELECT timezone FROM users WHERE id = $1`;
+    const q = `SELECT tz.name as timezone 
+               FROM users u 
+               JOIN timezones tz ON u.timezone_id = tz.id 
+               WHERE u.id = $1`;
     const result = await db.query(q, [userId]);
     return result.rows[0]?.timezone || 'UTC';
   }