Update k8s versions in CI

[kota2and3kan]

Description

This PR updates the versions of Kubernetes in the CI.

• Add 1.34, which is the latest version of Kubernetes.
• Remove 1.30, which is already the EoL version.
  • I confirmed that each major managed Kubernetes does not support 1.30 now.
    • EKS
    • AKS
    • GKE
    • OKE

You can see the test result in the following actions page:

• All charts other than monitoring stacks
  • https://github.com/scalar-labs/helm-charts/actions/runs/18363432564
• Monitoring Stacks
  • https://github.com/scalar-labs/helm-charts/actions/runs/18363436152
  • https://github.com/scalar-labs/helm-charts/actions/runs/18363439214
  • https://github.com/scalar-labs/helm-charts/actions/runs/18363441983

Please take a look!

Related issues and/or PRs

N/A

Changes made

• Add Kubernetes 1.34.
• Remove Kubernetes 1.30 since it has already reached EoL.

Checklist

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

I updated the official documents in the following PRs:

• https://github.com/scalar-labs/docs-internal-scalardb/pull/1621
• https://github.com/scalar-labs/docs-internal-scalardl/pull/720

Release notes

N/A

[gemini-code-assist]

Note

Gemini is unable to generate a summary for this pull request due to the file types involved not being currently supported.

[josh-wong]

LGTM! Thank you!🙇🏻‍♂️

[feeblefakie]

LGTM! Thank you!