chore: bump k8s version to 1.35

[hisarbalik]

Description

Changes proposed in this pull request (what was done and why):

• Bump k8s version to 1.35

Changes refer to particular issues, PRs or documents:

Traceability

• The PR is linked to a GitHub issue.
• The follow-up issues (if any) are linked in the Related Issues section.
• If the change is user-facing, the documentation has been adjusted.
• If a CRD is changed, the corresponding Busola ConfigMap has been adjusted.
• The feature is unit-tested.
• The feature is e2e-tested.

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[hyperspace-insights]

Summary

The following content is AI-generated and provides a summary of the pull request:

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What Changed

Bumps the Kubernetes version used in CI and local development from 1.34 to 1.35, updating the Gardener integration test matrix, the .env configuration, and the k3d cluster image.

Key Changes

• .env: Updates ENV_GARDENER_K8S_VERSION from 1.34 to 1.35.
• .github/workflows/gardener-integration.yml: Updates the k8s_version matrix entry from 1.34 to 1.35.
• .k3d-kyma.yaml: Updates the k3s image from v1.34.3-k3s1 to v1.35.4-k3s1.

Notes for Reviewers

This is a routine version bump with no logic changes. Verify that the k3s image tag v1.35.4-k3s1 is available in the internal registry before merging.

Release Notes Input

None.

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PR Bot Information

Version: 1.21.0

• Correlation ID: f015c188-580e-42e9-aabd-99d39c5dfd7d
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• Event Trigger: issue_comment.edited
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