This алёнка is a nickname for "елена" (Ye Linna).
As for why this chocolate is called this name, there are different opinions on the Internet. Some people say it's in memory of valentina tereshkova, the first Russian female astronaut, while others say it's in memory of Gagarin. However, I think another popular saying is more reliable, that is, the name Ye Linna is a very authentic Russian female name, just as we know that Russian male names represent Ivan, which is very representative. Moreover, in some childhood fairy tales, this name is also very meaningful and can remind people of childhood names, so this name is used. Anyway, there are different opinions, and this chocolate is a product of 1960 s. At that time, it was estimated that it was just to promote the brand and give it a catchy and memorable name. Who would want to give this brand a meaningful and story-telling name?