Promtail not compiled with systemd journal support

[dbruno74]

The grafana agent v0.36.1 is not supporting systemd journal as per the following warning:

Sep 13 13:57:28 ubuntu grafana-agent.grafana-agent[844875]: ts=2023-09-13T13:57:28.286907345Z caller=journaltargetmanager.go:29 level=warn component=logs logs_config=default msg="WARNING!!! Journal target was configured but support for reading the systemd journal is not compiled into this build of promtail!"

To reproduce:

• snap install grafana-agent
• configure $SNAP_DATA/etc/grafana-agent-yaml to include journal scraping, e.g.

  scrape_configs:
    - job_name: journal
      journal:
        max_age: 12h
        labels:
          job: systemd-journal
      relabel_configs:
        - source_labels: ['__journal__systemd_unit']
          target_label: 'unit'

• snap restart grafana-agent