Astalavista was the main warez search engine in the pre-google era and it was a play of words with altavista which was the most popular search engine at the time.
It wasn't a play on AltaVista -- Astalavista was actually older than AltaVista! It says so in the Wikipedia article you link to. I also only learned this mindblowing fact a few weeks ago.
https://en.m.wikipedia.org/wiki/Astalavista.box.sk