[RAC] [Observability] Create functional tests for alerts table pagination

[weltenwort]

📓 Summary

We should create functional tests for the table pagination on the Observability Alerts page.

✔️ Test cases

⚠️ When you pick this up, please spend a minute to think about and expand on these test cases. This is just an initial proposal.

• page size selector works
• pagination works
• table scrolls when page size large
• table doesn't scroll when page size small

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)