Remove flat list view in pages administration

• Type: Task
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: Master
• Component/s: Pages > Page Administration
• Labels: None
• Epic/Theme:
  • Pages_Administration
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/68663

LPS-86218 introduced a flat list view for pages administration. This view shows a flattened pages hierarchy tree. 

This view was meant to be particularly useful for small pages hierarchy by showing the pages in the order a user would get in an expanded tree view. However it's not been possible to respect the order of pages in this view. Without this, the view is not considered useful, so it's better to not show it to the user.