engine: Remove GetTimeZonesQuery usages

Removed last usages of the no loger existing GetTimeZonesQuery in
fronted and replaced with usage of the new TimeZoneType enum.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1011547
Change-Id: I575460833def554cfe5c8b6e4ec4a08c09167bb8
Signed-off-by: Martin Betak <mbetak@redhat.com>