Communication: Messages from oneself should not count towards unread messages

[HawKhiem]

Describe the bug

I logged in as Test User 20 and type something into some channels. When I click on to some other channels, the messages I typed count towards the unread messages even for myself

Screen.Recording.2024-12-17.001215.mp4

To Reproduce

1. Go to any course with communication enabled
2. Click on any channel and type in some messages
3. Click on another channel and see that the unread messages count for the previously mentioned channel has changed

Expected behavior

The unread messages should not take messages from oneself into account

Screenshots

No response

Which version of Artemis are you seeing the problem on?

7.8.0

What browsers are you seeing the problem on?

Chrome

Additional context

No response

Relevant log output

No response