Change messaging batch size and cron pattern (#6063)

Change messaging batch size and cron pattern to accelerate messages
import

packages/twenty-server/src/modules/messaging/common/services/messaging-fetch-by-batch.service.ts

@@ -19,7 +19,7 @@ export class MessagingFetchByBatchesService {
     messageIdsByBatch: string[][];
     batchResponses: AxiosResponse<any, any>[];
   }> {
-    const batchLimit = 50;
+    const batchLimit = 20;
 
     let batchOffset = 0;