High heap memory usage observed with DJL's HuggingFaceTokenizer implementation

## Current Behavior
- High heap memory consumption detected when using DJL's [HuggingFaceTokenizer](https://github.com/deepjavalibrary/djl/blob/master/extensions/tokenizers/src/main/java/ai/djl/huggingface/tokenizers/HuggingFaceTokenizer.java)'s tokenize method.
- Issue persists despite using the tokenizer as a singleton object.

## Impact
- Increased heap memory utilization affecting application performance.
- Potential memory management concerns in production environment.

## Questions
- Is the tokenize operation inherently memory intensive?
- Are there existing plans or recommendations to optimize memory usage?

TT: P198626352

Start with extensions/tokenizers/src/main/java/ai/djl/huggingface/tokenizers/HuggingFaceTokenizer.java, focusing on the tokenize method named in the report. Reproduce the high heap usage and profile the operation, comparing singleton and repeated use. Done means identifying the memory source and documenting or implementing a confirmed optimization or recommendation.

Written by the indexing model from the issue text.