Update annotations.md with Classic Load Balancer warning

[Ramneek-kalra]

Added a warning about creating Classic Load Balancers and best practices (specially for Normal or EKS Auto Mode). As tested internally with a customer, and found this gap.

Issue

There's no mentioning about "Classic Load Balancer" use-case as many customers do are interested to continue using it.

Description

When replicated, below are the steps:

• Created EKS Cluster/AutoMode Cluster
• Created sample App + Namespace & Service with "NodePort" Type [Didn't create any ELB]
• Edited the Service YAML manually using "kubectl edit svc <> -n <>" and changed the type to "LoadBalancer" and it created CLB on ELB Console

The same can't be done when a service is created via manifest using Type "LoadBalancer" as it will ask for "service.beta.kubernetes.io/aws-load-balancer-subnets" and it will make controller behave as NLB identification and no more CLB can be created, instead it will create NLB.

Changes made

• Added a note/warning for CLB Creation

Checklist

• [X] Added tests that cover your change (if possible)
• [X] Added/modified documentation as required (such as the README.md, or the docs directory)
• [X] Manually tested
• [X] Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! :exploding_head:

• [ ] Backfilled missing tests for code in same general area :tada:
• [ ] Refactored something and made the world a better place :star2:

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• :white_check_mark: login: Ramneek-kalra / name: Ramneek Kalra (7e1cae34ef79d832cea65c296788c04d1d871aab)

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