Google cannot censor. By definition. Neither can Yandex. Both can be censored however, although only the latter is.
The Russian government can & does censor, including, starting tomorrow, 15-year jail-sentences for „misleading statements“ about you-know-what.
https://www.google.com/search?q=censor%20definition
> examine (a book, movie, etc.) officially and suppress unacceptable parts of it.
https://www.google.com/search?q=officially
> with the authority of the government or other organization
I would call it censorship. But in those examples you listed, I would attribute it to the government and not the company. Because by removing those elements, they are not "exercising their rights to do so", they are "complying with local laws and regulations by doing so".
For a specific example: in Russia, "propaganda of homosexualty" (which includes something as trivial as explicitly acknowledging that one of the main characters is attracted to a person, or people in general, of the same sex) is against the law and is heavily punished.
So in reality, those companies only have two options: sell their product with those elements removed for that specific market or become unable to legally sell their product in that market at all.
Is it censorship? I would argue "yes", but I wouldn't say that the censorship is done by the company. If that action was required in order to be in compliance with local laws and regulations, I would call it for what it actually is - government censorship. After all, they are the ones making those laws and regulations that decide what is allowed and what needs to be removed.
It is true that it is impossible for Google to violate the 1st Amendment (unless they were nationalized first).
They're a private company. They can do whatever they want within the limits of the law. And the law doesn't say anything about not publishing something. Which can be done for purposes of censorship.
They're not a publisher. You have zero ability to post anything to Google, so there is nobody to be censored. They're an aggregator, and any aggregator can display whatever information they want.