Change Minio subchart to utilize OCI

Since we are consuming our own helm chart as a subchart here we can switch it to use the OCI version rather than a local file clone with kpt. In order to do this we will need to:

• Switch dependency to OCI repository (repository: oci://registry1.dso.mil/bigbang)
• helm dependency update: This is critical to make sure the chart is bundled locally for end users/airgap
• Delete the local copy (deps/minio)
• Validate everything functions as expected

If there are any places where this chart needs to be extended for Vault's use, make sure to submit these fixes upstream (in our minio chart) since we can't edit the chart when using OCI