[SPARK-48731][INFRA] Upgrade `docker/build-push-action` to v6

[panbingkun]

What changes were proposed in this pull request?

The pr aims to upgrade docker/build-push-action from v5 to v6.

Why are the changes needed?

https://github.com/docker/build-push-action/releases/tag/v6.2.0 https://github.com/docker/build-push-action/releases/tag/v6.1.0 https://github.com/docker/build-push-action/releases/tag/v6.0.2 https://github.com/docker/build-push-action/releases/tag/v6.0.1 https://github.com/docker/build-push-action/releases/tag/v6.0.0 https://docs.docker.com/build/ci/github-actions/build-summary/

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Pass GA. Manual observation as following: https://github.com/panbingkun/spark/actions/runs/9689581212

Was this patch authored or co-authored using generative AI tooling?

No.