Update prometheus rules for job rename

[jovial]

redfish-exporter-seed was renamed redfish-exporter in:

782f689

This updates the rules to match. Effectively making failed redfish scrapes warnings again.

[gemini-code-assist]

Code Review

This pull request updates Prometheus alert rules to reflect the renaming of the redfish-exporter-seed job to redfish-exporter. The changes correctly update the job name in the alert expressions. I have added one comment with a suggestion to fully align the alert rule with the intent described in the pull request (changing the severity to 'warning') and to improve its actionability by adding annotations.

[gemini-code-assist]

This alert rule could be improved in a couple of ways:

1. Severity: The pull request description states that the intention is to make failed redfish scrapes warnings again. To align with this, the severity should be changed from critical to warning.
2. Annotations: This alert is missing an annotations section, which is crucial for providing context when an alert fires. Adding summary and description annotations would make the alert more informative.

Here is a suggestion that incorporates these improvements:

  - alert: PrometheusTargetMissing
    expr: up{job="redfish-exporter"} == 0
    for: 15m
    labels:
      severity: warning
    annotations:
      summary: "Prometheus redfish-exporter target missing (instance {{ $labels.instance }})"
      description: "The redfish-exporter target has disappeared. The exporter might have crashed."