[Fluidstack] sky launch can leak instances when instance creation times out

[Xe]

With a config like this:

resources:
  accelerators: [A100:1]
  cloud: fluidstack

setup: "echo hi"

run: "python -m http.server 8080"

Fluidstack instance creation fails and the instances in the cloud are unable to be destroyed. The panel returns a "try again in 60 seconds" 500 error with this JSON body:

{"message":"Unable to terminate instance. Please try again in 60 seconds."}

Version & Commit info:

• sky -v: skskypilot, version 1.0.0.dev20241031
• sky -c: skypilot, commit c4eeeb5fb3ef64be0f05a727e119ac9266f8940f