Fix customizer state

QSFragment uses QSCustomizer#isCustomizing to determine what to show.
isCustomizing() = mCustomizing || mOpening.

Before this CL, if the customizer was hidden before it was fully opened,
it would thing it was still opening and QS would not be updated
correctly.

Test: manual
Fixes: 160509272
Change-Id: Iec9c896621502a1825f717f733b24bde2fe22509