[orchestrator] Handle ws disconnect

[pepoviola]

We need to add the logic to handle disconnections like API-WS: disconnected from ws://localhost:38063: 1006:: Abnormal Closure' and keep checking the migration progress.

Example: https://github.com/paritytech/ahm-dryrun/actions/runs/16747899314/job/47410718302

Thx!

[rockbmb]

This also happens in PET, or when using chopsticks in general.
I have not investigated deeply, but some RPC servers have low rate limits, which may get crossed with this kind of interaction.

I suggest keeping 2 (or a small set of) endpoints, and doing a round-robin between them when this happens.

[x3c41a]

I was testing the same but with local nodes and was still getting RPC timeouts and abnormal closures. My perception is that it's a chopsticks issue itself. I was also not able to get to the root cause of the problem...