feat: Add CentOS 8.0 binaries

[jopemachine]

Partially fix https://github.com/lablup/giftbox/issues/677.

Due to the difference in the glibc version, we cannot run Backend.AI on the CentOS8 image.
So adding CentOS8 krunner binary is needed.

And this PR also adds build scripts for backend.ai-jail and backend.ai-hook.

Notes

version issue

The version centos8.0 may not be correct because higher compatible versions like centos8.1 exist.
However, when using the name centos8, the current find_artifacts function finds this value invalid and skips.

backend.ai/src/ai/backend/agent/agent.py

Lines 417 to 423 in be3a305

	def find_artifacts(pattern: str) -> Mapping[str, str]:
	artifacts = {}
	for p in artifact_path.glob(pattern):
	m = self._rx_distro.search(p.name)
	if m is not None:
	artifacts[m.group(1)] = p.name
	return artifacts

Therefore, I think maybe we should use names like centos8.0 or centos8.x, or modify the implementation of the find_artifact.

zlib upgrade

It appears that ZLIB 1.2.11 is no longer distributed.
Therefore, the build-sftpserver.sh for CentOS 8.0 was built with ZLIB version 1.3.1.
But this PR does not include binary updates for other distributions.

Switching repository to the vault.centos.org

CentOS 8 support ended in late 2021, disabling its main repositories.
Switching to the vault.centos.org repository enables continued access to packages and updates for unsupported versions.

FROM centos:centos8
RUN sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-Linux-*

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Checklist: (if applicable)

• Milestone metadata specifying the target backport version
• Mention to the original issue

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[jopemachine]

• feat: Add CentOS 8.0 binaries #2220 👈
• main

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