Remove new camera flag functions and legacy code paths (#3071)

Signed-off-by: aaguilea <aaguilea@amazon.com>

Code/Editor/EditorViewportWidget.cpp

@@ -106,14 +106,6 @@ AZ_CVAR(
     bool, ed_visibility_logTiming, false, nullptr, AZ::ConsoleFunctorFlags::Null, "Output the timing of the new IVisibilitySystem query");
 AZ_CVAR(bool, ed_showCursorCameraLook, true, nullptr, AZ::ConsoleFunctorFlags::Null, "Show the cursor when using free look with the new camera system");
 
-namespace SandboxEditor
-{
-    bool UsingNewCameraSystem()
-    {
-        return true;
-    }
-} // namespace SandboxEditor
-
 EditorViewportWidget* EditorViewportWidget::m_pPrimaryViewport = nullptr;
 
 #if AZ_TRAIT_OS_PLATFORM_APPLE