Jessica Kiang War is blood and bombs and politics, but not in Alina Gorlova’s fascinating, fraught documentary “This Rain Will Never Stop.” Elliptically following 20-year-old Andriy Suleiman, a student Red Cross worker who “left one war for another” when his family fled Hasukah, Syria for his mother’s hometown of Lysychansk, Ukraine, this defiantly oblique, uncannily composed film instead reduces actual conflict to a dully thunderous, far-off roar.