There is no notification about new messages when message send via webhook

Description:

There is no notification about new messages when message send via webhook (neither tray notification nor at list of channels). It works like nothing was received (but if I open the channel, new messages looks like it has been read).

Steps to reproduce:

1. Make integration with GitLab https://docs.rocket.chat/guides/administration/admin-panel/integrations/gitlab
2. Do any action for GitLab send notification (about new commits, etc).

Expected behavior:

There should be a notification in the system tray + the channel name should looks like there is a new message (name is white)

Actual behavior:

There is no any notifications in the system tray and the channel's name there was no any new messages (name is grey)

Server Setup Information:

• Version of Rocket.Chat Server: 4.6.3
• Operating System: Ubuntu 18.04.6 LTS
• Deployment Method: snap
• Number of Running Instances: 1
• NodeJS Version: v14.18.3
• MongoDB Version: 4.2.17

Client Setup Information

• Desktop App or Browser Version: Desktop App, 3.8.7
• Operating System: Windows 10

Additional context

It may be related with #25529

Relevant logs:

Start with the GitLab integration and webhook message-handling entry points, then trace how those messages reach tray notifications and channel unread indicators. Reproduce the reported GitLab event on the stated setup and compare it with a regular message. Done means webhook-created messages trigger both notifications and the channel's new-message state.