Terminal tabs display @SID instead of @hostname

[kimlisa]

Description

When terminal creates a new session, it expects an API to return a session object with populated fields. It does not happen because of https://github.com/gravitational/teleport/blob/master/lib/web/apiserver.go#L1483
returns a dummy object. We need to refactor this method (perhaps remove it and add a slight changes to "connect" method) but it's also OK to return a hostname as part of the dummy object [EDITED] by @alex-kovoy

What happened:
terminal tabs display node server ID, instead of node's hostname.

What you expected to happen:
Display hostname name, it is easier to read and relate with.

How to reproduce it (as minimally and precisely as possible):
https://teleport-4-3-oss.practice.io:3080/web

1. Connect to a node via web UI
2. Notice the tabs login@serverID

Environment

• Teleport version (use teleport version): Teleport v4.3.2 git:v4.3.2-0-gc6d702ad8 go1.13.2