Replace deprecated batch_size with max_batch_size when using HybridCache
Author: mtreinik
Pull request: yes

# What does this PR do?

- Functionality remains the same, because property getter batch_size(self) returned max_batch_size anyways.
- This change just avoids an unnecessary warning about deprecation.

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Comments:
cc cache masters @gante @zucchini-nlp 

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