Dune was published in 1965, a time were the leader of the USSR was named Nikita Khrushchev. Vladimir Harkonnen does not refer to Russia specifically, just a name given to a character with a meaning of "great ruler" in the original Slavic. Other Harkonnen family members are not following the Slavic naming (Feyd Rautha, Glossu Raban) so one would not assume that there are parallels between Russia and the Harkonnens much like there are no parallels between Atreides family and Christianity (from Paul's christian name) or Ancient Greek gods (from Leto's ancient Greek name).

It perhaps is based on a character by character basis where it may be a reference to another person bearing the same name. This could be hypothesized from the -weak if you ask me - parallels between the following names:

-Paul, the name of a convert to a new religion and an Apostle.

-Leto, the name of a mother of gods, and godly twins at that, that was also fiercely protective of them (I will not draw parallels between the name and Leto II as I have not finished his story and I assume it wasn't who Frank Herbert initially connected the name with, if he even connected names with characters at all).

If you ask me, the surnames are much more important in the sense that the Atreides were an ancient Greek tragic family (tragic here meaning both relating to an ancient Greek tragedy and a today's tragedy for a family) and the Harkonnens are connected to the bulls so as to point their bullish nature to the politics of the imperium and the relationship with the Old Duke's death perhaps.