ru_UA locale: use copy "ru_RU" in LC_TIME (bug 25044)

Replacing incorrect abbreviated weekday names "Пнд", "Вто", "Срд"...
with correct ones "Пн", "Вт", "Ср"... makes the LC_TIME sections in
those two locales almost identical.  The only remaining difference
was that ab_alt_mon elements in ru_UA were lowercase while in ru_RU
they had the first letter uppercase, the latter was pointed as
a better choice by a native speaker.  This commit unifies LC_TIME
between ru_RU and ru_UA.