fix: route Granite models to TokenizersBackend to preserve tokenizer.json pre-tokenizer (#45813)
* fix: add Granite models to MODELS_WITH_INCORRECT_HUB_TOKENIZER_CLASS
Fixes #45812
* fix: route Granite models to TokenizersBackend to preserve tokenizer.json pre-tokenizer
previous fix was not triggering
Fixes #45812
* test: add tokenizer encoding test for Granite 4+
Verify that AutoTokenizer produces correct token IDs for digit strings, punctuation, and mixed alphanumeric inputs.
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Co-authored-by: Khoi-Nguyen Tran <kndtran@ibm.com>
Co-authored-by: Ita Zaporozhets <31893021+itazap@users.noreply.github.com>