Bug 33643: Add page-section to 'scan index' page in staff interface

Bug 33643: Add page-section to 'scan index' page in staff interface

This adds the white background. As we do on other pages I have
chosen to include the h2 heading within the page-section.

To test:
* Go to advanced search in staff interface
* Activate 'More options'
* Check checkbox for scan indexes
* Switch to author (especially when using Elasticsearch)
* Search for C
* On the result list verify there is no white background/page section
* Apply patch
* Repeat test - background should be present now

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Nicolas Giraud <nicolas.giraud@inlibro.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit fc9ca425c80d895168a6a8be48f94f16aeb34fce)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>