Remove Plex media server (#78)

## Summary
- Remove plex_metrics ansible role
- Remove Plex Grafana dashboard
- Remove Plex log collection from Alloy config
- Update indri-services-check to check Jellyfin instead of Plex

## Deployment and Testing
- [x] Unloaded plex-metrics LaunchAgent on indri
- [x] Deleted plex-metrics plist and script
- [x] Deleted plex.prom textfile
- [ ] Deploy Alloy config update
- [ ] Sync grafana-config to remove dashboard

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Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/78

ansible/playbooks/indri.yml

@@ -112,8 +112,6 @@
       tags: minikube
     - role: minikube_metrics
       tags: minikube_metrics
-    - role: plex_metrics
-      tags: plex_metrics
     - role: jellyfin
       tags: jellyfin
     - role: jellyfin_metrics