[APM] Solution navigation UI polish

[formgeist]

Summary

Related to #101044 there's a few UI polish items that we should clean up.

Polish

Adopt full page height of the content panel

As described in elastic/eui#4770 (comment) there might be a few problems that make the content panel not show in full height.

Move Service tabs navigation into the PageHeader

The EuiPageHeader component supports tabs, so we should make use of it and adopt our existing tabs navigation in this new way. That probably means re-positioning the View correlations button to somewhere else.

Wrap the Service map in a EuiPanel

Since the Service map no longer meshes with the page background, I think we can wrap it in a EuiPanel like other visualizations.

JVM detail page: Remove the horizontal rule below the detail header

Settings: Remove the light grey content background color

Agent configuration: Create view is not wrapped in the new page template, missing the navigation

Service inventory and Traces: Remove the panel padding around the tables

There's an option for EuiPanel to set paddingSize="none" for this instances.

Service maps height doesn't account for the new header height

That means the map canvas itself extends beyond the viewport height so there's a scroll.

Truncation or wrapping missing in the PageHeader title (blocked)

I've opened an issue in EUI (elastic/eui#4856) to see it's something we should implement case by case or generally in the PageHeader component, so let's wait for a response there.

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)