[telegraf] pod security admission restricted compatibility

It would be nice if the telegraf chart shipped with defaults that matched https://kubernetes.io/docs/concepts/security/pod-security-standards/#restricted which contains the current hardening best practices

Start by reviewing the telegraf Helm chart's current defaults alongside Kubernetes' Pod Security Standards restricted requirements. Identify which shipped defaults need to change for compatibility, and verify that the resulting chart configuration satisfies the linked restricted standard.

Written by the indexing model from the issue text.