[EKS] [request]: Manged Node Group allow launch template update without node rolling update

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**Tell us about your request**
Manged Node Group allows:
- Launch template update without node rolling update
- User to control when to trigger rolling update (like Auto Scaling Group instance refresh)

**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?**
### AMI patching frequency
Under security requirements, my company uses custom AMI and my team must performs AMI patching weekly. Even when nothing wrong, our application cannot meet SLA since nodes restart too often.

To meet patching frequency, we have an in-place patching script and this works fine for running nodes. But when NodeGroup scale up, new instance spawn using expired AMI.

### Gracefully introduce optional changes
Many other launch template params don't need to rolling update the entire nodegroup.

### How this option benefit my case
- Running nodes not disrupted and are in-place patched > meet SLA + security
- New nodes use new AMI
- Optional changes can be gracefully introduced to NodeGroup, eg: instance size, disk size, userdata,...

**Are you currently working around this issue?**
Falling back to self-managed Auto Scaling Group helps critical clusters meet SLA. But we also miss out NodeGroup important features: rolling update, honoring PDB, specifying max_unavailable,... I love the builtin rolling update mechanism, i just dont want it to trigger on all launch template changes.

For mandatory change, i have a custom script controlling ASG instance refresh + scale-in protection to achieve PDB.

**Additional context**
None

**Attachments**
None

No repository files, tests, or entry points are named; start by reviewing the EKS managed node group launch-template update behavior described in the issue. Done would mean defining support for updating the launch template without an automatic node rolling update, while allowing users to control when a rolling update occurs.

Written by the indexing model from the issue text.