Don't use deprecated vars of MinIO in starter

[fmuyassarov]

MINIO_ACCESS_KEY & MINIO_SECRET_KEY vars were deprecated in MinIO and replaced by MINIO_ROOT_USER and MINIO_ROOT_PASSWORD in minio/minio#11185 and this patch is updating starter-s3.yaml respectively.

Example logs of MinIO pod in from starter-s3.yaml deployment

WARNING: MINIO_ACCESS_KEY and MINIO_SECRET_KEY are deprecated.
         Please use MINIO_ROOT_USER and MINIO_ROOT_PASSWORD
API: http://10.244.3.5:9000  http://127.0.0.1:9000 

[k8s-ci-robot]

Hi @fmuyassarov. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[alvaroaleman]

/assign @chaodaiG

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, chaodaiG, fmuyassarov

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