Automate pre-update critical alert check

1. Proposed title of this feature request

Automate pre-update critical alert check.

2. What is the nature and description of the request?

OSDOCS-2427 landed docs:

Critical alerts must always be addressed as soon as possible, but it is especially important to address these alerts and resolve any problems before initiating a cluster update. Failing to address critical alerts before beginning an update can cause problematic conditions for the cluster.

In the Administrator perspective of the web console, navigate to Observe → Alerting to find critical alerts.

This RFE requests that check be automated, so customers don't have to remember to carry it out manually.

3. Why does the customer need this? (List the business requirements here)

Customers have enough going on in their lives, and if we can streamline updates for them by automating a currently-manual pre-update step, we:

• Reduce work for the admins who had noticed the docs calling for that manual step.
• Increase safety by performing the check for admins who had not noticed the docs calling for that manual step.

4. List any affected packages or components.

All relevant components are owned by the Over the Air Updates team, and the cluster-version operator is already able to query local Thanos (on most cluster flavors) to check for firing, critical alerts.