Increase prominence of deprecation logs in Upgrade Assistant

[cjcenizal]

For context, we originally surfaced deprecation logs prominently on the UA Overview page. Because many of these logs consisted of Elastic-triggered logs, which can't be addressed by the user, we decided to make the logs less prominent in the UI (#118659). Based on the cross-linked issue, I think we've removed this problem so it's safe to increase the prominence of the logs again.

I had a chat with @pgomulka today, in which he expressed concern that there is still critical cluster/data-level information in our deprecation logs which users should address before upgrading. He cited the Joda-Java date format migration as one example of something that's only being surfaced in logs. Perhaps there are others.

This seems like good justification to raise the prominence of the deprecation logs in UA. I hesitate to move all of the content from the deprecation logs page back into an Overview step because that would really bloat the Overview. How about we add a new step called "Address deprecation logs"? This step could consist of a short description, a simple status (disabled / has no logs / has X logs), and a link to the deprecation logs page.

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[alisonelizabeth]

++ This makes sense to me

[alisonelizabeth]

Fixed by #126277