[ci] use real aarch64 runners instead of emulation with QEMU

[jameslamb]

Description

GitHub Actions now offers GitHub-hosted aarch64 runners:

• [ci] remove Docker volumes during Azure cleanup #6760 (comment)
• https://github.blog/changelog/2025-01-16-linux-arm64-hosted-runners-now-available-for-free-in-public-repositories-public-preview/

These should be used for this project's 1 aarch64 CI job, which produces manylinux2014_aarch64 wheels. The existing approach emulating aarch64 using QEMU should be removed.

Benefits of this work

• faster CI
  • *these jobs regularly take 60-90 minutes to run, MUCH longer than any other single CI Job run on every PR here (example build link)
• easier debugging

Acceptance criteria

• aarch64 wheels are built and tested on runners which physically have arm64 CPUs, instead of using emulation
• manylinux_aarch64 wheel builds are automatically built and attached to releases when new GitHub releases are created.... or the release checklist includes an item saying something like "attach aarch64 artifacts to release and upload to package repositories"

Approach

Existing job to replace:

LightGBM/.vsts-ci.yml

Lines 218 to 226 in e61bcbe

	###########################################
	- job: QEMU_multiarch
	###########################################
	variables:
	BUILD_DIRECTORY: /LightGBM
	COMPILER: gcc
	PRODUCES_ARTIFACTS: 'true'
	pool:
	vmImage: ubuntu-22.04

Example of using a GitHub ACtions job to upload artifacts for the release:

LightGBM/.github/workflows/python_package.yml

Lines 85 to 90 in e61bcbe

	- name: upload wheels
	if: ${{ matrix.method == 'wheel' && matrix.os == 'macos-14' }}
	uses: actions/upload-artifact@v4
	with:
	name: macosx-arm64-wheel
	path: dist/*.whl

Notes

This could also be a path to addressing #5035