ci: test gpu on self-hosted runners

[galargh]

Partially resolves #1775

This introduces the following changes:

• changes the CI workflow to be triggered only on pushes to master and all pull requests
• migrates the test release job back to a self-hosted runner (no GPU needed)
• migrates the test no default features job back to a self-hosted runner (no GPU needed)
• reintroduces the test gpu jobs and puts them on self-hosted runners

The test gpu jobs are currently put on g6e.xlarge machines because we only have limited number of resources (vCPUs) available. When we are granted the quota increase, I'll migrate the jobs to more powerful runners.

If approved, similar PRs will be created for other repositories we identified as needing self-hosted runners.

I tested the updated job here: https://github.com/filecoin-project/rust-fil-proofs/actions/runs/15614277342/job/43982899999

It will also be tested as part of the PR flow.

[BigLep]

• migrates the test release job back to a self-hosted runner (no GPU needed)
• migrates the test no default features job back to a self-hosted runner (no GPU needed)

I assume you mean github-hosted runners (since no special hardware needed)? Or I guess you saying you're moving back to a non-gpu self hosted runner.

[BigLep]

Sweet. I'm not sure how you figured out the nvdia drier install stuff, but I'm glad you got it working. Thakns.

[galargh]

• migrates the test release job back to a self-hosted runner (no GPU needed)
• migrates the test no default features job back to a self-hosted runner (no GPU needed)

I assume you mean github-hosted runners (since no special hardware needed)? Or I guess you saying you're moving back to a non-gpu self hosted runner.

Yes, sorry, I should have been more clear. I meant moving to our non-gpu self-hosted runner.

[vmx]

See inline comment, the rest looks good.