Remove custom helper for content item in find local council
Remove custom helper for content item in find local council

In 490d01f1bdc46be64a0e8ba6ef67ccb81a94dafb we replaced the hardcoded
content item response in the `FindLocalCouncilController` with a version
that spoke to the content store.  However, we also inlined our own
`setup_content_item_and_navigation_helpers` method instead of re-using
the version in `ApplicationController`.  This means we stopped setting
the `govuk:section` meta tag, but also means we'll miss out on any
other changes that we want to apply globally.  We revert back to using
the `ApplicationController` version to avoid this.

alphagov/frontend,alphagov/frontend,alphagov/frontend,alphagov/frontend