Switch package releases from standalone packaging server to s3 release bucket.

[niedbalski]

Bug Report

Releases should go into s3 releases bucket and replace the usage packaging server.

• Ensure package releases are correctly signed and published on s3 releases bucket
• Synchronise previous releases into the s3 release bucket via rsync.
• Ensure old and new signing gpg keys are updated and documented.
• Update the fluent-bit-infra to point the packages.fluentbit.io domain to the s3 bucket.
• Enable stats for the release buckets. (Either via cloudflare or on s3 directly).
• Send download stats to Grafana dashboards.

To Reproduce

N/A

Additional context

[patrick-stephens]

Need to ensure we cover repo metadata signing in packaging/update_repos.sh as well as using SHA256 digests. This seems to be required for FIPS mode on RHEL.

#3617
#3618

Both should be testable in the smoke tests.

[patrick-stephens]

• Add a smoke test run to verify from the new domain URL for simple installation checks.

[patrick-stephens]

New CNAME up: https://github.com/fluent/fluent-bit-infra/blob/91feb5d61448fdf74484b593089731df3f3f2e6e/terraform/domains.tf#L179
It is accessible at packages-test.fluentbit.io.s3.amazonaws.com

[niedbalski]

@patrick-stephens can we kick this off and RIP the server?

[patrick-stephens]

Not without Windows build and checksums, plus cert issues.

[patrick-stephens]

Checksums should be done now, just waiting on #5599 to fully deprecate the Appveyor builds although we can transition without it.

[patrick-stephens]

OTE now, getting per-object stats is tricky for S3 so we are using the S3 buckets as the source of truth but hosting on a server that replicates them with the relevant metrics then available.