[Enhancement] Switch etcd-backup-restore Integration Tests to Use LocalStack for S3 Emulation

[seshachalam-yv]

Enhancement (What you would like to be added):

LocalStack should be integrated into the etcd-backup-restore integration test job. This would enable the tests to use LocalStack for S3 emulation, effectively removing the dependency on real AWS S3 buckets.

Motivation (Why is this needed?):

By leveraging LocalStack for S3 emulation, we can increase the accessibility and cost-efficiency of our testing process. This is due to LocalStack's ability to replicate AWS services locally, thereby mitigating the need for actual AWS infrastructure.

Approach/Hint to the implement solution (optional):