No e2e tests for sessions

[jkeat]

We currently don't have e2e tests for session actions such as:

• Student makes a help request
• Volunteer joins a session
• Student and volunteer exchange chat messages in session
• Volunteer prevented from joining a session which is already fulfilled
• After participant ends their session, the "finish" button brings them to the feedback form
• ...etc

For now, we don't need to test whiteboard drawing interactions