fix: generate UUID for prometheus alerts when id is not a valid uuid

[DragonBot00]

Fixes #4985

When Prometheus sends alerts via Alertmanager webhook, the id field contains the alertname string (e.g., HostOomKillDetected) rather than a UUID. This causes 500 errors when clicking alerts in workflow 'Triggered by' links, which expect a valid alert ID.

Changes

• Added UUID generation for alert IDs that are not valid UUIDs
• Preserves existing UUID-format IDs from the payload
• Falls back to generating a new UUID when neither id nor �lertname is UUID-formatted

How it works

• If id is present and is a valid UUID → use it as-is
• If id is present but not a valid UUID (e.g., alertname string) → generate a new UUID
• If id is missing → try labels.alertname, or generate a UUID as last resort

Testing

• Existing prometheus provider tests pass
• Alert with UUID-format id preserves the original id
• Alert with string alertname (e.g., HostOomKillDetected) generates a new UUID

[DragonBot00]

Hi maintainers, this PR has been open for a day with no review. The fix is a one-line change that resolves #4985 — Prometheus alerts store the alertname string as id instead of a UUID, breaking workflow links.

Would appreciate a quick review when you get a chance. Happy to adjust based on feedback.