Fix clock stlye floaring sheet height

Sometimes, due to the race condition, the clock content height can be
small since we are getting the height too late after the slider is
taken.

Instead, we only get the clock style list's height and add the slider's
height in case if we need to show both.

Test: Manually tested. See bug.
Bug: 418437663
Flag: com.android.systemui.shared.new_customization_picker_ui
Change-Id: I97c92f72f234f5f185b9634c492575d9cda2b3fe