fix: shell open gives unfriendly message on terminated

[NicholasBlaskey]

Description

Fix an issue where terminated shells would give a verbose error message like

shell (id: fcace6b5-5ea4-4cd3-a390-1a12500a600f) is ready.
disconnecting websocket
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/Users/garrett/miniforge3/envs/det/lib/python3.9/threading.py", line 980, in _bootstrap_inner
kex_exchange_identification: Connection closed by remote host
Connection closed by UNKNOWN port 65535
To reconnect, run: det shell open fcace6b5-5ea4-4cd3-a390-1a12500a600f

Test Plan

Start and kill a shell then try to open it

We should expect the message to be this

det shell open $ID
CLI version 0.26.1-dev0 is less than master version 0.26.1-rc0. Consider upgrading the CLI.
Waiting stopped: task has been terminated.                                      
task has been terminated.

Commentary (optional)

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

Ticket

[netlify]

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