Don't use `LayoutLMv2` and `LayoutLMv3` in some pipeline tests
# What does this PR do?

These 2 models require **different input format** than those of usual text models. See the relevant code block at the end.
The offline discussion with @NielsRogge is that **these 2 models are only for DocQA pipeline**, despite they have implementations for different head tasks. 

Therefore, this PR **removes these 2 models from being tested (pipeline) in the first place**, instead of skipping them at later point.
**IMO, we should also remove these models being used in the pipeline classes (except DocQA)** if they are not going to work. But I don't do anything on this.

**`LayoutLMv3` with `DocumentQuestionAnsweringPipeline` (and the pipeline test) is still not working due to some issue. We need to discuss with @NielsRogge to see if it could be fixed, but it's out of this PR's scope.**

### relevant code block
https://github.com/huggingface/transformers/blob/daf53241d6276c0cd932ee8ce3e5b0a403f392b7/src/transformers/models/layoutlmv3/tokenization_layoutlmv3.py#L610-L625
_The documentation is not available anymore as the PR was closed or merged._<|||||>Merge now as this PR only touches tests. Feel free to leave a comment if any @NielsRogge 