Fix flicker for Mobile data & Wi-Fi page

Both "Mobile data usage" & "Non-carrier data usage".

By,
1. Add header in onCreate() instead of onViewCreated()
2. Keep the space for Spinner, and preload initial cycles
3. Keep the space for 3 usage summaries

Bug: 191730864
Test: manual
Change-Id: I8c309c5f51ce6290383a2d10f75e41d0f207d61a