Improve testing coverage of private pki

[mjnagel]

Currently our Private PKI testing covers two main applications:

• Grafana (login test to ensure Keycloak's cert is accepted)
• Authservice/Istiod (login test to ensure Keycloak's cert is accepted)

With #2337 we introduced automatic mounts for a number of the other applications in UDS Core. However, we don't actually have any test behaviors ensuring that the mounted CAs are being utilized by the underlying applications.

Definition of done: Tests added to cover pods/services interacting with systems using the Private PKI, validating that they do properly trust those certificates.

[mjnagel]

Some initial thoughts:

• Several of these could probably be covered by configuring minio in cluster to use the self-signed certs:
  • Loki: point to minio for storage of logs, validate read/write paths
  • Vector: add an additional output direct to "s3" (minio)
  • Velero: backup to "s3" (minio)
• Prometheus: Scrape an external endpoint (virtualservice) that is exposing metrics. Possibly could do this with podinfo very easily? Ensure the scrape works.
• Alertmanager and Falco Sidekick: Unsure on target here, but both would likely need to send alerts to an external location using the private pki. Falco sidekick could potentially send to grafana's external interface?