[Security Solution] No results screen for Alerts page should be simplified

[snide]

When no alerts are returned, there's no reason to show the graph / metrics views. Suggestion would be to keep the visual display of the page simple and only display items that might change the results.

An example of this pattern can be seen in the Discover application, where the results and graph are removed, and the only controls shows are those that might let the users see data (search, time, index selector)

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)