Fix profile photo chooser

The underlying Dialog API changed when it returns true for isShowing()
in a way that broke our profile photo chooser, but it turns out it was
an intended change and we were depending on it in a way we shouldn't
have been. Instead we'll just keep track of whether we were showing the
dialog by using an already existing boolean flag that gets set before we
start the photo collection activity.

Fixes: 110101157
Test: make -j RunSettingsRoboTests
Change-Id: I166230e85142c348b6760e436324261f2a41f1e0