[feature] Spark operator should use Pod Identity

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#### What is the outcome that you are trying to reach?

EKS has released Pod Identities to help manage IAM rights for pods https://docs.aws.amazon.com/eks/latest/userguide/pod-identities.html
The Spark operator solution still uses IRSA but it would be great to have it use Pod Identity instead

Start by reading the EKS Pod Identities documentation linked in the issue, then inspect how the Spark operator currently uses IRSA. Update the operator’s identity configuration to use Pod Identity instead, and verify that the Spark operator can obtain the required IAM permissions without IRSA.

Written by the indexing model from the issue text.