Resolve "Add documentation point and garage smoke test for Garage"

General MR

[6.2.0-bb.0]

Changed

• bb-common 1.0.2 -> 1.5.0
• gluon 1.1.2 -> 1.1.7
• mimir-distributed 6.1.0 -> 6.2.0
• registry1.dso.mil/ironbank/opensource/grafana/enterprise-metrics v2.17.15 -> v2.17.18
• registry1.dso.mil/ironbank/opensource/grafana/mimir 3.1.2 -> 3.2.0
• registry1.dso.mil/ironbank/opensource/grafana/rollout-operator v0.38.0 -> v0.39.0
• registry1.dso.mil/ironbank/opensource/memcached/memcached 1.6.43 -> 1.6.45
• registry1.dso.mil/ironbank/opensource/nginx/nginx 1.30.3 -> 1.31.4
• Updated tests/test-values.yaml to use filesystem backend (formerly test-values-classic.yaml)
• Updated upstream.minio.enabled comment to recommend Big Bang Garage for in-cluster storage

Added

• Added chart/values.schema.json enforcing upstream.minio.enabled: false and rejecting minio-tenant key
• Smoke test for Garage object storage via CI dependency stack
• CONTRIBUTING.md

Removed

• Removed minio-instance sub-chart dependency; Big Bang MinIO is no longer bundled with Mimir

Umbrella Branch

mimir-remove-minio

Relevant logs/screenshots

N/A

Linked Issue

Relates to #133 (closed)

Relate to #132 (closed)

Upgrade Notices

MinIO deprecation: Big Bang MinIO support in Mimir will be removed in Mimir 6.2.0-bb.0. If you are currently using minioObjectStorage.enabled: true, plan migration to an alternative S3-compatible backend before upgrading to Mimir 6.2.0-bb.0.

For in-cluster dev/test environments, Big Bang Garage is the supported replacement. See the Garage Package Integration document for guidance.

No action required for deployments already using an external S3 backend (s3ObjectStorage.enabled: true).