add package manager proxy cache for build jobs

[msarahan]

Use new service, setup action at: https://github.com/nv-gha-runners/setup-proxy-cache

[ajschmidt8]

Seeing these warnings in the downstream workflows.

Fortunately these arguments default to true anyway, so it should have no effect on this initial testing. But we'll want to fix it nonetheless

[msarahan]

Rebased to 25.02 and removed the pip/conda specifiers that @ajschmidt8 pointed out.

[ajschmidt8]

Can we get some new downstream tests to ensure everything is working as expected?

[msarahan]

Looks like it is setting the env vars as expected. I don't know that I can comment on any performance improvements, but the work here at least looks non-disruptive.

https://github.com/rapidsai/rmm/actions/runs/13057200836/job/36431299581?pr=1801

[bdice]

FYI, I merged the upstream so the PR diff would no longer show CUDA 12.8 related changes. Nothing functional should have changed.

[ajschmidt8]

Looks like it is setting the env vars as expected. I don't know that I can comment on any performance improvements, but the work here at least looks non-disruptive.

https://github.com/rapidsai/rmm/actions/runs/13057200836/job/36431299581?pr=1801

There's a Slack thread floating around where we identified that there may not be any particular performance enhancements since conda/PyPI could already be using CDNs. However, workflows should be more reliable against network issues by using the proxy.

[msarahan]

/merge