Migrate from `aws_s3_bucket_object` to `aws_s3_object` to fix deprecation warnings

[arianvp]

aws_s3_bucket_object is deprecated and we should move away from it.

In order to do that without downtime we need to wait for the release of open tofu 1.10.0 which should be out soon:

opentofu/opentofu#2898 (comment)