SSH runtime hammers failing remote service

[spikecurtis]

On Coder's internal dogfood server, there are recorded instances where mux attempts to SSH into a single Coder workspace approximately 1000 times per minute. The workspace was in the process of stopping, so each individual SSH command fails after querying the workspace state a single time, but we record thousands of queries while the end user says they were starting up mux workspaces.

cc @sreya @deansheather