fix: use release-specific templated names

[monrax]

Summary

Small fix: template release-specific resource names to prevent collisions with existing releases.

What changed

• Use new helper template for init script ConfigMap name in both charts/graylog/templates/config/init-graylog.yaml and charts/graylog/templates/workload/statefulsets/graylog.yaml
• Use template in name field in charts/graylog/templates/policy/pdb/datanode.yaml
• Use template in name field in charts/graylog/templates/service/ingress/graylog-forwarder.yaml

Linked issues

This closes #72

Checklist

• Tests added/updated
• Documentation updated
• This PR includes a new feature
• This PR includes a bugfix
• This PR includes a refactor

Testing Checklist

Static Validation

• Linter check passes: helm lint ./charts/graylog
• Helm renders local template sucessfully: helm template graylog ./charts/graylog --validate

Installation

• Fresh installation completes successfully: helm install graylog ./charts/graylog
• All pods reach Running state: kubectl rollout status statefulset/graylog
• Helm tests pass: helm test graylog

Functional (if applicable)

• Web UI accessible and login works
• DataNodes visible in System > Cluster Configuration
• Inputs can be created and receive data

Upgrade (if applicable)

• Upgrade from previous release succeeds
• Scaling up/down works correctly
• Configuration changes apply correctly

Specific to this PR

• Follow all steps in "How to reproduce?" section in linked issue, and verify no errors are encountered.

Notes for reviewers

• Verify all tests above pass
• Sync up with the author before merging
• The commit history should be preserved - use rebase-merge or standard merge options when applicable