Requires AWS access/secret key when offload driver is set to aws-s3

[nathanclayton]

Describe the bug
When the offload driver is set to aws-s3, you have to set a secret with the values of AWS_ACCESS_KEY_ID and AWS _SECRET_KEY_ID. These are not necessary if you're using IAM roles tied to the Kubernetes service account to grant access to the S3 bucket

To Reproduce
Steps to reproduce the behavior:

1. Create a new deployment where offload driver is set to aws-s3 and the secret name is blank
2. Deploy
3. The following error will pop up in the broker stateful set:

create Pod pulsar-broker-0 in StatefulSet pulsar-broker failed error: Pod "pulsar-broker-0" is invalid: [spec.containers[0].env[0].valueFrom.secretKeyRef.name: Invalid value: "": a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'), spec.containers[0].env[1].valueFrom.secretKeyRef.name: Invalid value: "": a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')]

Expected behavior
Able to deploy with the aws-s3 offload driver without needing to use access keys

Desktop (please complete the following information):

• OS: AWS EKS 1.29

Additional context
The line that is causing this appears to be here.

[lhotari]

@nathanclayton Thanks for the issue report. Would you have a chance to contribute the fix to this problem?

[nathanclayton]

@lhotari - PR made as #466