Fix jumping slider in split shade

In BrightnessMirrorController constructor, setup the slider mirror's paddings from resources so that it is align to the slider's position. We need to call updateResources() in the constructor to setup the mBrightnessMirrorBackgroundPadding to be used by setLocationAndSize().

Fixes: 230478558
Test: android.platform.test.scenario.sysui.quicksettings.SwipeBrightness
Change-Id: If0ca3acc2df031f61613446797021a2cb33cabf2