[ML] Cosmetic issues with anomaly detection job details fly-out

[sophiec20]

Kibana version:
8.18.2 and Serverless

1. The paging indicator has strange blobs
2. I think we should default to 25 rows per page as there's room in the flyout
3. Should Open jobs list actually be a button to Manage Jobs ? -- Managing jobs seems like a more relevant action to take here. Opening a list is hardly worth the effort. (this is a separate discussion to the cosmetic issues)
4. (see below) The visual boundary of the JSON viewer is weak

[elasticmachine]

Pinging @elastic/ml-ui (:ml)