chore: add index for the files attribute on the messages collection (RocketChat#38087)

Author: pierre-lehnen-rc

packages/models/src/models/Messages.ts

@@ -54,6 +54,7 @@ export class MessagesRaw extends BaseRaw<IMessage> implements IMessagesModel {
 			{ key: { expireAt: 1 }, expireAfterSeconds: 0 },
 			{ key: { msg: 'text' } },
 			{ key: { 'file._id': 1 }, sparse: true },
+			{ key: { 'files._id': 1 }, sparse: true },
 			{ key: { 'mentions.username': 1 }, sparse: true },
 			{ key: { pinned: 1 }, sparse: true },
 			{ key: { location: '2dsphere' } },