Verify that a test in `LayoutLMv3` 's tokenizer is checking what we want

[SaulLu]

I'm taking the liberty of opening an issue to share a question I've been keeping in the corner of my head, but now that I'll have less time to devote to transformers I prefer to share it before it's forgotten.

In the PR where the LayoutLMv3 model was added, I was not very sure about the target value used for one of the tests that had to be overridden (the value was 1 in one of the previous commits and then changed to 0). The comment I am referring to is this one: https://github.com/huggingface/transformers/pull/17060#discussion_r872265358 .

Might be of interest to @ArthurZucker

[ArthurZucker]

Thanks! Will try to get familiar with this 😉