fix(chat): change disconnenct message if connection is lost

fix(chat): change disconnenct message if connection is lost

If a connection is interrupted due to network issues, a user closes his tab, or a call-in user hangs up, we send a participant disconnected message with the reason being connection_lost.

This commit changes the chat message displayed in that case from ... was removed from the meeting at ... to ... left the call at ....

(cherry picked from commit 43d599b0)

Closes #3449 (closed)