kibana [Search] [Playground] Re-enable Full width view + fix scrollbar issue

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Summary

Fixes two issues:

the view should be full width, so removing restrictWidth option
in serverless, the content view was scrollable, even when the vertical content did not exceed the screen.

On scrollbar fix:

grow adds a min-block-size: max($minHeight, 100vh). minHeight is by default 460px. 100vh which doesn't take into account the header, adding a scrollbar with extra size from header. A fix ive seen other solutions do is either specify 0 in minHeight (which omits the block-size css style which is a side-effect) or switch off grow (min-block-size:$minHeight). I've opted for grow=false as our children components manage the height.

Without fix

With fix

Delete any items that are not applicable to this PR.

[ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
[ ] Documentation was added for features that require explanation or tutorials
[ ] Unit or functional tests were updated or added to match the most common scenarios
[ ] Flaky Test Runner was used on any tests changed
[ ] Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
[ ] Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
[ ] If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
[ ] This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
[x] This was checked for cross-browser compatibility
[x] Tested in both serverless and stateful