Until 1989, to be precise.
Incidentally, during Perestroika the society was changing at such a high rate that what was hard to imagine just three months before was becoming routine. Now looking back 20+ years it is so difficult to reconstruct the timeline.
Well, I know when Perestroika started, but I gave it a bit of a margin, since I can't say for sure when precisely it affected this discrimination. It's known to be gone for sure in the 1990s. Could be, it started in 1989.
In general such discrimination against Jews in Moscow State University was commonplace until the beginning of 1990s, and is gone since then.