chore(deps): update infrastructure dependencies to latest versions

[edersonbrilhante]

Description

This pull request updates multiple infrastructure dependencies to their latest stable versions.
These updates are generated automatically by Renovate to keep our Terraform and Helm dependencies up to date and aligned with upstream releases.

Updates Included

• Helm Release: splunk-otel-collector → v0.140.0
• Terraform Module: terraform-aws-github-runner → v6.9.1
• Terraform Module: terraform-aws-modules/eks/aws → v21.9.0

Notes

• These upgrades are minor or patch-level changes and should be backward compatible.

• Please review any upstream changelogs or release notes for additional context:

  • [Splunk OTel Collector Helm Chart](https://github.com/signalfx/splunk-otel-collector-chart/releases/tag/v0.140.0)
  • [terraform-aws-github-runner](https://github.com/github-aws-runners/terraform-aws-github-runner/releases/tag/v6.9.1)
  • [terraform-aws-modules/eks/aws](https://github.com/terraform-aws-modules/terraform-aws-eks/releases/tag/v21.9.0)

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Type of Change

• Bug Fix
• New Feature
• Breaking Change
• Refactor
• Documentation
• Other (please describe):

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Checklist

• I have read the [contributing guidelines](/CONTRIBUTING.md)
• Existing issues have been referenced (where applicable)
• I have verified this change is not present in other open pull requests
• Functionality is documented
• All code style checks pass
• New code contribution is covered by automated tests
• All new and existing tests pass

[artemburlaka]

LGTM