Store the executor hostname in clickhouse

[vanja-p]

This will allow evaluating experiments where we want a feature to be on/off on a whole machine.

Initially, I want to evaluate #8655.

[tylerwilliams]

Any idea how this will affect storage (since it's a potentially long string)?

[vanja-p]

Any idea how this will affect storage (since it's a potentially long string)?

invocation_uuid takes about 1%, and it's probably longer and harder to compress then hostname, so I think less than 1% of additional storage.

[maggie-lou]

If we want to avoid doing this for now, we could test this on baremetal nodes and hard code which ones are assigned to the experiment because they have static names

[vanja-p]

I would like to some way to compare execution statistics (exec and pause time for firecracker actions at least) between machines in and out of the experiment, so as long as I can do that, it works for me. Can we isolate individual baremetal hosts when looking at prometheus metrics?

I think it would be good for us to have a general way of doing this across cloud and bare metal, but maybe it's not so important.

hard code which ones are assigned to the experiment because they have static names

How would we do this? In the Go code, or creating a separate deployment?