We sometimes end up with stale wheel uploads from previous runs of a Buildkite agent. The result is that commit wheels are being overwritten from old build jobs - effectively breaking the wheel build logic.
Example:
This Agent: https://buildkite.com/organizations/ray-project/agents/4b955117-2f6c-4849-b703-3457daf69f89
- builds wheels (in post-wheels tests) for a35ebc945b
- and then runs both the Ray CPP worker and the Train + Tune tests in 6746e9f
- Usually these two tests shouldn't provide artifacts at all, but they do - these are the wheels from a35ebc945b though! Meaning these are uncleaned leftovers from the first build task.
- See here for proof of artifact upload: https://buildkite.com/ray-project/ray-builders-pr/builds/27622#d11bc514-ebd8-4e0c-a2ce-826b9bad27de
The solution is thus to always clean up the artifacts directory in the worker, i.e. `rm -rf /artifact-mount/*`
This PR adds two of such clean up instructions - once before commands are run and once after artifacts are uploaded. We can probably just do either, but it doesn't hurt to have both.
