[DEVPLAT-4317] Remove aws-sdk-go v1

[Neurostep]

Description

In this PR we are removing the usage of deprecated aws-sdk-go (deprecation announcement).

Most of internal Go services are migrated to aws-sdk-go-v2.

Checklist

• Prefixed the PR title with the JIRA ticket code
• Performed simple, atomic commits with good commit messages
• Verified that the commit history is linear and commits are squashed as necessary
• Thoroughly tested the changes in development and/or staging
• Updated the README.md as necessary

Related links

• DEVPLAT-4317
• https://aws.amazon.com/blogs/developer/announcing-end-of-support-for-aws-sdk-for-go-v1-on-july-31-2025/

---

Note

Drops aws-sdk-go v1, migrates instrumentation and Kafka MSK IAM auth to aws-sdk-go-v2, removes deprecated APIs, and updates tests/dependencies.

• Breaking changes:
  • Remove pkg/instrumentation.InstrumentAWSSession and kafka.Config.AwsSession.
• Instrumentation (AWS):
  • Keep v2-only InstrumentAWSClient using dd-trace v2 middleware; delete v1 session wrapper.
  • Update aws_test.go to use v2 (config, s3, resolver types) and new span/tag expectations.
• Kafka (MSK IAM SASL):
  • getAwsMskIamSaslOption now accepts only *aws.Config; remove session-based path and helper.
  • Assume role via v2 sts client; adjust imports and calls.
• Dependencies:
  • Remove github.com/aws/aws-sdk-go v1 and related transitive deps; tidy go.mod/go.sum.

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[terranisu]

LGTM 👍🏻