Consider adopting renovate-generate workflow from cluster-provider-gardener

[maximiliantech]

What would you like to be added?

Adopt the renovate-generate workflow from cluster-provider-gardener:

1. Add .github/workflows/renovate-generate.yaml that triggers on renovate/** branches and runs task generate
2. Update renovate.json with gitIgnoredAuthors to prevent infinite loops from bot commits

Reference implementation:

• Workflow: https://github.com/openmcp-project/cluster-provider-gardener/blob/main/.github/workflows/renovate-generate.yaml
• Commit: openmcp-project/cluster-provider-gardener@27af628

Why is this needed?

• Generated files are automatically updated when dependencies change
• Reduces manual intervention on Renovate PRs
• Keeps all service-providers consistent with cluster-provider-gardener

Acceptance Criteria

• service-provider-template has the renovate-generate workflow and updated renovate.json
• Roll out to all existing service-providers (not just the template)