Migrate away from bitnami/minio

[mgruner]

Reason: #353

Ideas

• Switch to https://artifacthub.io/packages/helm/cloudpirates-minio/minio - seems to be well maintained.
• Use https://github.com/minio/operator - not sure if this is maintained.
• Drop minio subchart completely, ask users to deploy their own S3 storage or use an existing cloud service.

[mgruner]

@monotek what do you think? Would it be an option to drop the subchart completely?

[Sigtechnica]

If it would possible to use an existing cloud storage service aws s3 (drop-in replacement ovh , ...)

[monotek]

I would go with the cloudpirates chart, as we're already using their charts anyway.
Droping it would mean users need to buy some extra service.

[mgruner]

@monotek do you have a suggestion for the data migration?

[monotek]

Should be straight forward:

• Before the update copy the data to a local directory via "kubectl cp" (https://kubernetes.io/docs/reference/kubectl/generated/kubectl_cp/)
• Do the update which installs new minio chart
• Copy local data to new container / PVC with kubectl cp