[EKS] [request]: Allow running all managed add ons as non-root where possible

### Community Note

* Please vote on this issue by adding a 👍 [reaction](https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to the original issue to help the community and maintainers prioritize this request
* Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do not help prioritize the request
* If you are interested in working on this issue or have submitted a pull request, please leave a comment

**Tell us about your request**
We are being instructed by our security team that all pods in our EKS clusters need to run as non-root or go through a lengthy exception process for each container that cannot fit this requirement. We would like to be able to run the EBS and EFS driver pods as non-root, or at least a subset of the containers in the pod if there are containers that fundamentally cannot run as non-root.

**Which service(s) is this request for?**
EKS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
All of the containers in the EBS and EFS driver pods run as root, and while the helm chart does offer the ability to set a security context on each container, this is not exposed through EKS Add-ons, and even if it was, there is no documentation for which container are safe to set to a non-root user and what UID/GID should be used.
It would also be good to be able to drop all Linux capabilities and only grant capabilities relevant to the task associated with each container, along with any other securityContext options to lock down the pods.

**Are you currently working around this issue?**
Currently just gathering information to prepare for a security exception, assuming this isn't something that can be resolved easily.

**Additional context**
This would extend to beyond just EBS and EFS pods. I haven't done a full check of all EKS Add-ons to see where they're running as non-root where they might not need to be

**Attachments**

Start by inventorying the EBS and EFS driver pods and the Helm chart securityContext options mentioned in the issue, then compare them with what EKS Add-ons exposes. Extend the investigation to other managed add-ons as scope permits. Done should identify which containers can run non-root, the required UID/GID and capabilities, and how those settings are exposed or documented.

Written by the indexing model from the issue text.