Fixing notifications in split shade when customizing QS

- disabling changing container margins/paddings when customizer is shown in split shade
- removing notifying stack scroller about customizer changes in split shade - this should not be needed anymore as now expanded QS and QS customizer always take full height of the screen

Bug: 193223224
Test: manual
Change-Id: Ice02529d1f6b78c8ff885be3270734ac23ee80e8