we already have a localized timezone
we already have a localized timezone

aside: I'm pretty sure we can drop `tz_abbrev` and just use `timezone`
directly everywhere, assuming
    get_timezone_for_user(...)
is the same as
    get_timezone_for_user(...).localize(datetime.utcnow()).tzinfo
which I suspect is the case.

dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq