Enable TruncationStrategy override for pipelines (#9432)
* Enable TruncationStrategy override for pipelines
* Update isort.
* Fixing test
* Fixing text_generation pipeline.
* Using same DummyTok as other PR for easier merge later.
* Some more import guards.
* Remove bogus file.
* Do not pass `generate_kwargs` to `_parse_and_tokenize`.
@patrickvonplaten
* Removed DummyTok.
* Doc quality.
